

UNITED STATES DEPARTMENT OF AGRICULTURE 

BULLETIN No. 1037 

Contribution from the Bureau of Plant Industry 
WM. A. TAYLOR, Chief 


Washington, D. C. PROFESSIONAL PAPER August 19, 1922 


THE CONTROL OF SAP-STAIN, MOLD, AND 
INCIPIENT DECAY IN GREEN WOOD 
WITH SPECIAL REFERENCE 
TO VEHICLE STOCK 

By 

NATHANIEL Of HOWARD, Pathologist 
Office of Investigations in Forest Pathology 

(In cooperation with the Forest Products Laboratory of the United States Forest Service, 

Madison, Wis.) 


CONTENTS 


Page 


Introduction. 1 

Sap-Stain. 3 

Other Fungous Organisms Causing Sur¬ 
face Discolorations in Green Timber . 12 

Factors Which Favor the Growth of Sap- 
Stain and Mold Fungi.14 


Page 

Durability of Stained or Molded Wood. 17 
Losses Due to Sap-Stain or Mold. ... 18 


Control Measures ..21 

Summary. 50 

Literature Cited.52 



WASHINGTON 

GOVERNMENT PRINTING OFFICE 
1922 










































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library of congress 

“EC&IVED 

SEP 201922 

DOCUMENTS DIVISION 





UNITED STATES DEPARTMENT OF AGRICULTURE 


BULLETIN No. 1037 

Contribution from the Bureau of Plant Industry 
WM. A. TAYLOR, Chief. 


Washington, D. C. PROFESSIONAL PAPER August 19, 1922 


THE CONTROL OF SAP-STAIN, MOLD, AND INCIP¬ 
IENT DECAY IN GREEN WOOD, WITH SPECIAL 
REFERENCE TO VEHICLE STOCK. 1 

By Nathaniel O. Howard, Pathologist , Office of Investigations in Forest 

Pathology. 

(In cooperation with the Forest Products Laboratory of the United States Forest Serv¬ 
ice, Madison, Wis.) 




CONTENTS. 


Page. 

Introduction__?>_ 1 

Sap-stain__ 3 

Other fungous organisms causing 
surface discolorations in green tim¬ 
ber__ 12 

Factors which favor the growth of 

sap-stain and mold fungi_ 14 


Page. 

Durability of stained or molded 


wood_ 17 

Losses due to sap-stain or mold__ 18 

Control measures_:_ 21 

Summary___1_ 50 

Literature cited_ 52 


INTRODUCTION. 

During periods of transit and storage, previous to its ultimate 
manufacture, green timber containing a high percentage of sapwood 
often suffers considerable damage. This is particularly true during 
the late spring and summer months when deterioration brought about 
mainly through a discoloration of the sapwood, known as sap-stain, 
sometimes necessitates degrading on a large scale. This staining 
of timber has occasioned severe losses in Europe as well as in the 
United States, and many expensive investigations have been made to 
determine the nature of the stain and to discover a satisfactory 
remedy. 

1 The writer wishes to acknowledge his indebtedness to Mr. C. J. Humphrey, in charge 
of the Laboratory of Forest Pathology, Bureau of Plant Industry, in cooperation with 
the Forest Products Laboratory, Madison, Wis., for facilities and for advice in outlining 
the work ; to Dr. Charles Thom and Miss Margaret B. Church, of the Bureau of Chem¬ 
istry, for the identification of mold fungi; to Mr. IT. D. Tiemann, physicist and specialist 
in kiln drying, Forest Products Laboratory, Madison, Wis., for the loan of photographs ; 
to Mr. Joseph Ashcroft, of Toplar Bluff, Mo., for cooperation in the experimental dipping 
of spokes; and to all others who, by information, suggestion, or criticism, have con¬ 
tributed to the preparation of the manuscript of this bulletin. 

75579°—22-1 






















2 BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. 

The molding of green timber has frequently been confused with 
sap-stain as well as with incipient decay. However, in so far as the 
production of permanent stain or the effect upon the durability of the 
wood is concerned, molding is of comparatively little importance. 
Incipient decay caused by true wood-destro}dng fungi, on the other 
hand, is of great importance. 

Early in the year 1918 the attention of the Office of Investigations 
in Forest Pathology was called to staining and molding occurring 
in green raw material by the wood-stock committee representing the 
National Implement and Vehicle Association and other Aehicle and 
vehicle parts manufacturers through the Forest Products Labora¬ 
tory of the United States Forest Service, Madison, Wis. The pres¬ 
ent investigation arose in connection with raw hardwood stock used 
in the manufacture of escort wagons and artillery carriages. A 
large quantity of this material was at that time being sawed or 
turned, largely from green instead of seasoned stock and shipped 
green from the saw. In some cases it was found necessary to cull 
severely such stock at destination, owing to the presence of mold, 
stain, or incipient decay which had developed during transit and 
while in storage. In cooperation with the Forest Products Labora¬ 
tory and the wood-stock committee, a questionnaire 2 was sent to a 
number of the contractors for Army vehicles and parts and to pro¬ 
ducers of wood stock. Personal investigations were also made of 
the conditions existing at 45 mills and factories engaged in the saw¬ 
ing of timber, dimension stock, and veneer, or in the manufacture 
of airplanes, furniture, flooring, handles, vehicles, and vehicle parts. 
Most of these mills were located in the central and southern portions 
of the United States and were directly concerned in the production 
of war material. The object of both questionnaire and personal 
investigations was to gain information concerning the general sani¬ 
tary conditions existing in the woods, railway cars, sheds, ware¬ 
houses, and kilns; the details of manufacture of many vehicle parts; 
the extent of deterioration occurring in green raw material; the finan¬ 
cial losses occasioned thereby; and, particularly, any practical meth¬ 
ods of handling green wood stock that would prevent the develop¬ 
ment of stain and mold therein. 

The investigations showed that many of the firms had experienced 
considerable pecuniary losses, which were due to the necessity of 
using a high percentage of green stock; to a shortage of cars, re¬ 
sulting in the congestion of material in the woods and railroad 

2 National Implement and Vehicle Association and other Vehicle and Vehicle Parts 
Manufacturers. Information Division of the Wagon and Vehicle Committee and the 
Wheel Manufacturers’ War Service Committee. Wood Stock Committee. Sap-stain and 
mold in green lumber. Nat. Implement and Vehicle Assoc., etc., Bui. 24, 2 p., 1 fig. 
1918. A. B. Thielens, chairman. Multigraphed. 



SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 


3 


yards; to lack of time for the proper air seasoning or kiln drying 
preparatory to shipment; and, finally, in some cases to a failure to 
understand the conditions necessary to safeguard the stock while 
in storage or in transit. Many of these losses due to emergency will 
be considerably reduced upon return to normal conditions. 

Some manufacturers consider it important that, in order to over¬ 
come losses due to checking, certain kinds of stock produced at many 
of the smaller mills be shipped to them in a green rather than in a 
partly seasoned condition. They claim that these mills, not being 
equipped for the proper drying of stock preliminary to shipment, 
make it necessary for the manufacturer to insist that material from 
such sources be shipped in a green condition to the factory, where 
suitable means for storage and drying are maintained. Close atten¬ 
tion must be paid to the handling of this material in transit or in 
storage if deterioration due to fungi is to be prevented. 

The necessity for a careful conservation of timber in the United 
State is becoming more and more apparent ( 53, 3 5^ 4 ). Measures, 
then, that will assist in preventing or reducing losses due to fungous 
attacks are of importance. 

This bulletin presents a brief review of our knowledge of sap- 
stain and mold, a consideration of the causal organisms responsible 
for such deterioration in green wood stock, the results of the new 
investigations, and finally a summary of some of the important meth¬ 
ods of control. 

SAP-STAIN. 

The “bluing,” or sap-stain, of pine timber has been observed in 
Europe for many years. Both Hartig ( 17 , 18 ) and Frank ( 11 ) 
refer to it in their investigations of plant diseases. Rudeloff ( 36 ) 
studied the effect of blue stain on the strength of pine wood. Munch 
( 31 ) not only examined the properties of blued coniferous wood but 
also investigated the causal organisms and determined the optimum 
conditions for their development in the wood. In the United States 
considerable attention has been given to the subject by such investi¬ 
gators as Von Schrenk ( 4 ^ 1 , 43 , VO <> Hedgcock ( 19 , 30 ), Rumbold 
37 , 38 ), Weiss and Barnum ( 56 , 57 ), and Bailey ( 5 ). Many of the 
investigations have been made in connection with the sap-stain of 
hardwoods as well as conifers. 

3 The serial numbers ( italic) in parentheses refer to “Literature cited” at the end of 
this bulletin. 

* These two reports on Senate Resolution No. 311 by the Forest Service of the United 
States Department of Agriculture may be obtained from the Superintendent of Docu¬ 
ments, Government Printing Office, Washington, D. C., at 25 cents and 5 cents, respec¬ 
tively, per copy. 




4 BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. 

DEFINITION OF SAP-STAIN. 

The term “ sap-stain ” refers to the blue, green, brown, or red dis¬ 
coloration which often may be observed in the sapwood of timber 
derived from several kinds of broad-leaved and coniferous trees. 
It must not be confused, however, with the superficial discolorations 
produced mechanically, i. e., by collections of dirt and coal dust, by 
deposits from the drip in leaky cars and sheds, or from the condensed 
moisture in kilns. Such deposits may occur upon heartwood as well 
as sapwood. Neither should it be confused with the common blue- 
purple stain apparent when rusty saws are used on certain green 
wood, such as oak. This stain results from the reaction between the 
tannic acids of the wrnod and the iron compounds from the saw. 
Finally, it must not be confounded with the variously colored super¬ 
ficial growths of molds or the more or less deep seated sap-rot, with 
its brown to bleached appearance and its tendency to produce a 
punky consistency of the sapwood itself. 

There are two quite generally recognized classes of sap-stain: (1) 
The chemical stain, said to be produced by chemical reactions brought 
about through the agency of certain oxidizing enzyms present in the 
wood itself; and (2) fungous stains known to be caused by several 
species of fungi. 

CHEMICAL STAINS. 

r * ’ ’ •• . • -»- « • ’ 

Chemical stains due to enzyms cause discolorations in both the sap- 
wood and the heartwood of sugar pine and hard maple (Tiemann, 
<51, p. 185; also Pratt, 34, p- 805-307). Such stains develop during 
air drying, particularly under warm and humid conditions, or in 
the kiln, and give more or less permanent discolorations to the wood, 
to wit, a brown stain in sugar pine (fig. 1) and a'cherry color in 
hard maple. These defects cause degrading (34) and often result in 
financial losses. According to Bailey (-5), when freshly cut sapwood 
of alder, birch, cherry, or red gum is exposed to the air during ex¬ 
tremely warm and humid Aveather, chemical reactions often take place 
and within a few hours produce colored substances in the Avood. Bailey 
(5) states that the microscopic examination of sections of such wood 
indicates that the colored substance deA r elops particularly within the 
pith rays and the parenchyma cells. He states that certain soluble 
enzyms which assist in the oxidation of organic compounds and are 
of prime importance in the nutrition and groAvth of living organ¬ 
isms are widely distributed in plants and animals and may also pro¬ 
duce post-mortem discolorations of certain organic compounds (see 
also Clark &, 9). Yoshida (59) discovered in 1883 that an oxidizing 
ferment is responsible for the oxidation of the latex in certain species 
of Rhus and the formation thereby of black varnish, or lacquer. 
Investigations have also shown that discolorations in fruit juices, 


SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 


5 



vegetables, cereals, mushrooms, and various soft plant tissues are 
brought about through the agency of certain oxidizing ferments, the 
oxidases and the peroxidases (Aso i,Clark, 8, 9\ Kastle, 27). 
These ferments are sometimes distinguished by the production of a 
strong blue color in a tincture of guaiacum when used in the presence 
of oxygen or hydrogen peroxid 
(Haas and Hill, 16 , p. 383). 

Bailey (6) states that the ac¬ 
tivity of these oxidizing enzyms 
increases with the rise in tem¬ 
perature to a certain point, 
which may be called the opti¬ 
mum, and then decreases as the 
temperature is raised above this 
point. In almost every case, ac¬ 
cording to the same authority, 
the activity is entirely destroyed 
before a temperature of 100° C. 

(212° F.) is reached. He also 
states that the activity of these 
oxidizing ferments is dimin¬ 
ished or destroyed by certain 
antiseptics and by other chemi¬ 
cal substances. According to 
Aso (i, 2), such substances as 
tannin, sodium fluorid, and so¬ 
dium silicofluorid, interfere 
with the color reactions nor¬ 
mally produced by oxidases. 

Bailey (5) notes the strong 
similarity existing between the 
oxidizing activities of these en- 
z} r ms and the chemical reactions 
responsible for certain kinds of 
sap-stain, namely, post-mortem 
oxidation with change of color 
produced by solutions in con¬ 
tact with the air and the similar variations in the activity of the 
discoloring agency in relation to variations in temperature. 

If discolorations in sapwood are due to the activity of oxidizing 
enzyms, which, as has been shown, are rendered inactive by exposure 
to a temperature of 100° C. (212° F.), a logical prophylactic measure 
would be the submersion of timber in boiling water. Bailey ( 5 ), 
during the spring of 1910, performed certain dipping experiments. 


Fig. 1.—Board of sugar pine, showing 
chemical stain. The unstained area in 
the lower half of the illustration indi¬ 
cates the position of a crosser during the 
kiln treatment. The crosser afforded pro¬ 
tection from oxidation. Photographed by 
H. D. Tiemann. 














6 BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. 

He found that when 1 by 3 by 6 inch boards of alder (Alnus incana 
Moench), white or gray birch (Betula populifolia Marsh), paper 
birch (Betula papyrifera Marsh), and various trees belonging to the 
rose family (Rosacea?) were immersed in boiling water and then 
stacked under cover they would remain unchanged in color. Those 
boards which had been immersed in the boiling water and then 
placed in the most unfavorable conditions of high humidity and 
temperature in the open and exposed to the direct rays of the sun 
scorched on the surface. With the exception of this superficial 
scorching, no discoloration of the wood took place. On the other 
hand, untreated boards that had been cut from the same portion of 
the tree and subjected to similar conditions of temperature and 
humidity stained rapidly. Bailey (5) found that the rapidity and 
the depth to which the stain penetrates the wood varies with the 
temperature and the moisture, hot and humid weather being espe- 
cially favorable for the production of stain. From a consideration 
of the results obtained, he concludes that sap-stain caused by oxidiz¬ 
ing enzyms can be readily prevented by dipping the timber for a few 
minutes in boiling water. 

Though chemical stains give more or less trouble in kiln-dried 
maple flooring and sugar-pine lumber, the discolorations may be 
prevented to an extent by the use of comparatively low temperatures 
(120° to 125° F.) and correspondingly low humidities (50 to TO per 
cent; Tiemann, 5T, p. 185). Because of their limited distribution 
and the fact that they do not impair the strength or durability of the 
timber, chemical stains in general can hardly be considered as having 
very great economic importance. 

FUNGOUS STAINS. 

The second class of stains is produced by fungi. These fungi are 
disseminated by means of minute bodies known as spores. The 
spores may be produced in countless numbers and are blown about 
by the wind, washed along by the rain, or carried by animals, 
particularly insects. When, under favorable humidity and tem¬ 
perature conditions, they happen to lodge upon a substratum, such 
as the moist green sapwood of woods that contain the requisite food 
material, the spores may germinate and give rise to a mass of fine, 
usually septate threads, sometimes colorless at first, but often becom¬ 
ing darkened with age. This vegetative portion of the fungus is 
known as the mycelium, and the individual threads are called hyphae. 
In some cases the hyphae probably penetrate the wood but little, 
growing for the most part over the surface; in others, they may enter 
the sapwood through the medullary or pith rays. This does not result 
in the disintegration of the walls of the wood cells to any appreciable 


SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 


7 


extent. The starches, sugars, and oils stored in the sapwood and pith 
rays, together with the contained air and water, probably exert an 
influence upon the advancing hyphse and limit largely the growth of 
the fungus to the sapwood and the pith rays, where the sap-stain is 
mainly to be found. Practically no invasion of the heartwood takes 
place (Yon Sclirenk, ^7, p. 19). (PI. I, fig. 3.) 

THE SAP-STAIN FUNGI. 

The relation of a fungus to the bluing of wood was first noted by 
Hartig (77, 18). He describes the organism which causes the so- 
called “ bluing ” of conifers, especially dead or dying pine that has 
been injured by caterpillars, as C eratostoma piliferum. He notes 
that it ma}^ also appear in damp firewood. According to Hartig, 
the brown mycelium very quickly penetrates the trunk through the 
medullary rays. He states that probably on account of the de¬ 
ficiency in moisture content the heartwood is avoided by the mycelium, 
whereas the sapwood often becomes quickly invaded and decomposed. 
Although described by Fries (13; see also Berkeley, d), who placed 
it in the genus Sphaeria, the fungus was later transferred by Fiickel 
(14\ see also Ellis and Everhart, 10) to the genus Ceratostoma. Sac- 
cardo (39) still later divided the genus Ceratostoma and placed those 
species which possess colorless spores in a new genus, Ceratostomella. 
Winter (58) ,in a subsequent revision of the family included the fungus 
as Ceratostomella pilifera Fries under the new genus. It is now 
known as Ceratostomella pilifera (Fries) Winter (Engler and 
Prantl, 29). 

Figure 2 illustrates the fruiting bodies of this fungus. With the 
aid of a magnifying glass one may often see them clearly as stiff 
black hairs, approximately 1 millimeter (l/25th of an inch) in 
length, 5 swollen at the bases, and forming, en masse, a dark hairy 
covering on the ends and tangential surfaces of stained sapwood. 
These growths when well developed are sometimes referred to by 
lumbermen as “ whiskers.” 

Many species of Ceratostomella have been listed by Saccardo (Jfi). 
Though no reference is made to the fact, it is probable that a. number 
of these stain wood. 

The life histories of many species of Ceratostomella found on 
stained wood have been worked out by Yon Schrenk (41 ), Hedgcock 
(19 ), and Rumbold (37) in this country and by Munch (31) in 
Europe. In connection with the study of several chromogenic fungi 
which discolor wood, Hedgcock developed in culture a conidial stage 
of Ceratostomella superficially resembling Cephalosporium. Munch 
and Rumbold associated a Graphium stage with the development of 


5 In some species the length may exceed 2 millimeters. 



8 


BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. 


Ceratostomella. During the extensive culture work of Hedgcock, 
however, extending over a period of four or five years and involving 



Fig. 2.—Mycelium and fruiting bodies of “ blue-stain ” fun¬ 
gus: 1, Tangential section of “blue” wood; 2, cross sec¬ 
tion of “ blue ” wood; 3, cross section of pith ray; J,, 
young fruiting body of the “ blue-stain ” fungus ( Cerato- 
stomella fiUifera) ; 5, mature fruiting bodies of the “blue- 
stain ” fungus ; 6, two fruiting bodies of the “ blue-stain ” 
fungus; 7, two spore sacs with spores of the “ blue-stain ” 
fungus; 8, spores of the “ blue-stain ” fungus; 9, top of 
beak of fruiting body of Ceratostomella pilifera just after 
the discharge of the spore mass. (After Von Schrenk 
(32), pi. 7.) - 

a number of species of Ceratostomella from a variety of sources, no 
Grapliium stage of this fungus was ever reported. 


I 














































































Bui. 1037, U. S. Dept, of Agriculture. 


Plate I. 



Fig. 1.—Radial section of bull pine, showing hyplue of the blue-stain fungus growing in the pith 
rays. Fig. 2.—Tangential section of the saine, showing many small hyphse growing into 
the adjoining cells. Fig. 3.—Log of southern yellow pine containing sap-stain. Fig. 4.— 
Mycelium of mold growing between hard-maple boards in a kiln. Fig. 5.—Mold on the end of 
a sawed red-oak billet. Fig. 6.—Maole billet containing sap-rot, a condition brought about 
through the agency of wood-destroying fungi. The surface has been polished to show more 
clearly the bleached and disorganized condition of the sapwood. (Figs. 1 and 2 are from Von 
Schrenk (41), pi. 8; fig. 4 is from a photograph by H. D. Tiemann.) 




























































































Bui. 1037, U. S. Dept, of Agriculture. 


Plate ! I 



Examples of Wood Infection.—II. 

Fig. 1.—Artificially infected blocks of red oak and white oak in the tile chamber ready for the 
steaming experiments performed at the Madison laboratory. The large white areas of 
mycelium on the ends of the blocks in the upper four rows are wood-destroying fungi and 
probably developed as a result of infection in the log. Fig. 2.—Sawed felloes of oak (species 
not known). Note the abundant growth of mold which had developed in the material during 
shipment and while in storage. Photographed by H. D. Tiemann. 



























SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 


9 


Hedgcock (10) identified the following species of Ceratostomella 
as responsible for the discolorations produced in certain woods: 

C. pilifera (Fr.) Wint., in the sapwood of several species of pine (Pinus), 
fir (Abies), oak (Quercus), and ash (Fraxinus). 

C. schrenkiana n. sp., in short-leaf pine ( Pinus echinata Mill.). 

C. ecliinella E. and E., in freshly cut heartwood and sapwood of beech ( Fagus 
atropunicea (Marsh) Sudworth). 

C. capillifera n. sp., in wood of red gum ( Liquulamber styraoiflua L.). 

C. pluriannulata n. sp., in blue sapwood of red oak ( Quercus rubra L.). 

C. minor n. sp., in Arizona pine ( Pinus arizonica Eng.). 

C. exigua n. sp., in dead and dying trees of scrub pine ( Pinus virginiana 
Mill.). 

C. moniliformis n. sp., in red gum ( Liquidambar styraciflua L.). 

Miinch (31) split up Ceratostomella pilifera Fries into a series 
of new species, as follows: 

1 Ceratostomella pint, the important blue-stain fungus of pine. » 

2. The pilifera group, distinguished by the secondary fruiting bodies: 

(а) C. piceae, with an associated Graphium stage, possibly Graphium 
penicillioides Corda, in species of pine and fir. 

(б) C. cana, with an associated but unclassified Graphium stage. This 
species he also found in pine wood. 

(c) C. coerulea, having no associated Graphium stage. 

With these species of Ceratostomella Miinch includes two unrelated 
fungi, Endoconidioplxora coerulescens and Cladosporium sp., as 
causing discolorations in coniferous timber. 6 

Yon Schrenk (^7), in his studies of the “ blue wood” in dead and 
dying stands of the western yellow pine (Pinus ponderosa Laws.), 
found that the spores of Ceratostomella blown about by wind or 
carried by insects are often deposited in the exposed ends left by the 
breaking of branches or in the holes made by the bark and wood 
boring beetles. There, under the favorable conditions which usually 
prevail, they germinate and readily produce in a short time many 
colorless, branching hyphae. The hyphae grow into the bark tissues, 
then into the cambium, and from there into the medullary rays. 
With age the hyphae take on a brown hue. 

According to Von Schrenk ( 1+1. pp. 18, 19), “ one of the first effects 
seen after the hyphae have entered the medullary ray cells is the grad¬ 
ual solution of the walls separating the medullary ray cells from one 
another (fig. 2, 7, 3). The walls which separate the ray cells 

from the neighboring wood cells may become very thin, as shown in 
the middle ray (fig. 2, 7), but they are rarely dissolved entirely. The 
intermediate walls, on the other hand, entirely disappear. This 

6 In a recent publication, C. J. Humphrey (23) describes a fungus, Lasiosplweria 
pezizula (B. and C.) Sacc., as the cause of a blue-black stain in certain hardwoods, par¬ 
ticularly beech and red gum. More detailed information concerning this fungus, as well 
as certain species of Ceratostomella, is given by E. E. Hubert (21). 

75579°—22-2 




10 


BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. 


leaves a tube, with a cross section having the shape of the cross sec¬ 
tion of the ray, extending into the trunk from the bark. This tube 
is sometimes filled entirely with a mass of brown hyphae, the larger 
number of which extend in the direction of the ray (PI. I, figs. 1 
and 2). From the ray cells some hyphae make their way into adja¬ 
cent wood cells (fig. 2, 0; PL I, figs. 1 and 2). 7 They grow along 
these, both up and down (fig. 2, 1 ), giving off branches to other wood 
cells. In this manner the whole wood body becomes penetrated by 
the brown hyphae in a very short time after the first infection. The 
number of hyphae in the wood cells proper, excluding the medullary 
ray cells and the cells of the wood parenchyma, is very small indeed. 
This is probably due to the fact that the fungus finds scant material 
upon which to live in the wood cells. The liypliae are apparently 
able to puncture the unlignified walls here and there, but they stop 
at that point. The writer was not able to demonstrate that the hyphae 
could attack the lignified walls. In other words, the 4 blue ’ fungus 
is one which confines its attack to the food substances contained in the 
storing cells of the trunk and to the slightly lignified walls of these 
storing cells. 1 ’ According to the same authority (^f, p. 19), the resin 
ducts may be attacked in like manner (fig. 2, S\ PI. I, fig. 2). 

In the case of sawed timber it is quite probable that the fungous 
spores falling upon the surface of the sap wood find there the mois¬ 
ture and food material necessary for germination. Subsequently they 
give rise to a mass of mycelium, many of whose hyphae enter the 
wood through the exposed medullary or pith rays and then probably 
invade the surrounding tissue, as explained by Von Schrenk. 

SUSCEPTIBILITY OF VARIOUS WOODS TO SAP-STAIN FUNGI. 

The sapwoods of many kinds of timber are susceptible to sap-stain, 
though the degree of susceptibility varies considerably. Among the 
conifers southern yellow pine, western yellow pine, sugar pine, and 
the spruces seem to be readily stained and in the case of the broad¬ 
leaved trees, red gum, red oak, white oak, and ha^kberry seem to be 
particularly susceptible. 

Often there is a considerable difference between a species when 
grown on the dry uplands and the same species when grown under 
the moist conditions characteristic of the lowlands (Von Schrenk and 
Spaulding, H). This difference in woods of the same species may be 
even more marked when grown in essentially different climates 
(Spaulding, Jf8). It seems to be the opinion of many lumbermen that 
timber grown in the South is more susceptible to fungous attacks 
than timber grown in the North. If differences in susceptibility do 

7 E. E. Hubert (22) observed in the wood of scrub pine and northern white cedar 
hyphae of Ceratostomella sp., which had penetrated tracheids and wood fibers for a dis¬ 
tance of several cells from the medullary rays. 




SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 11 

exist in such woods it is difficult to state whether they are due to 
dissimilarities in mechanical structure, to the relative proportions of 
contained air and water, or to the variety and amounts of stored food 
present in the wood parenchyma and medullary rays. It is probable 
that differences in environmental conditions, i. e., temperature and hu¬ 
midity as affecting the growth of the fungi, are important factors 
directly responsible (Roth, 35 , p. 55-56). 

STRENGTH OF “ BLUED ” WOOD. 

Smce the wood fibers are not appreciably impaired by the growth 
of the blue-stain fungus, there should be no apparent loss in the 
strength of the invaded wood. Rudeloff (36) found that the compres¬ 
sion strength of pine is not affected by the presence of bluing fungi. 
Tests on the stained wood of western yellow pine conducted at Wash¬ 
ington University, St. Louis, Mo. (Von ijSchrenk, ])1) and later at 
the Forest Products Laboratory, Madison, Wis. (Weiss, 56 ; Weiss 
and Barnum, 57) proved that there is practically no diminution in 
the end compression or cross-breaking strength and hardness of the 
stained as compared with the unstained wood. In the case of heavily 
stained shortleaf pine, however, tested at the latter institution, there 
was found to be a slight decrease in the strength, toughness, and 
hardness as compared with unstained wood having the same moisture 
content. It may be safely stated that blued wood is practically as 
strong as unstained wood. 

CAUSE OF THE COLOR IN “ BLUED ” WOOD. 

The cause of the blue color in the wood has never been satisfac¬ 
torily explained. R. Hartig (17, p. 66) ascertained that it arises 
from the presence of the brown fungous hyphae in the intercellular 
spaces. According to Von Schrenk (1+1, p. 18, 25-26), it appears in 
the wood when the colorless mycelium begins to take on the brown 
hue characteristic of the mature fungus. Microscopic examination 
of the wood fibers taken from the blued wood reveals no indication 
of a blue color. While extracts of the blue wood with alcohol, ether, 
benzol, chloroform, alkalis, and acids differ in appearance from 
those obtained from clear wood, yet no blue tinge is apparent. Von 
Schrenk ( U , p. 26) suggests that possibly “ there is some pigment 
with a blue element in the ‘blue ’ wood which is so faint that its de¬ 
tection in thin microscopic sections becomes almost impossible.” 
Hedgcock ( 19 , p. 110-111) states that “ the brown color of the fungus 
apparently contains traces of a blue pigment whose color is trans¬ 
mitted by the wood cells of the pine more readily than the brown 
color.” Mfinch (31, p. 3) concludes that the color is due to the ar¬ 
rangement of the mycelial threads in the wood. He cites, as some- 


12 BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. 

what similar examples, the blue color of thin milk, cigarette smoke, 
and the clear sky, wherein very fine particles are held in suspension 
in a transparent medium. 

OTHER FUNGOUS ORGANISMS CAUSING SURFACE DISCOLORA¬ 
TIONS IN GREEN TIMBER. 

In addition to the blue-stain fungi, there is another group, the 
molds, which commonly occur upon the freshly cut surfaces of green 
timber when stored under moist, warm, and stagnant conditions (pi. 
I, fig. 5; PI. II, figs. 1 and 2). Molds are occasionally found growing 
vigorously upon timber in kilns (PI. I, fig. 4). This is especially 
noticeable when the atmosphere of the kiln is exceedingly moist or 

saturated and the temperature ranges 
from 90° to 110° F. 8 or from 110° to 
130° F. (Tiemann, 51 , p. 186-187). 

Hedgeock (19) showed that the 
blackening and browning so common 
in the green sapwood of pine (Finns 
sp.), poplar (Populus sp.), tulip (Liri- 
odendron sp.), red gum (Liquidarribar 
sp.), oak (Quercus sp.), maple (Acer 
sp.), and several other woods can 
often be traced to species of Graph- 
ium. He cites: 

G. ambrosiigerum n. sp., on Arizona pine 
{Finns arizonica Eng.). 

G. eumorphum Sacc., on wild red rasp¬ 
berry (Rubus strigosus ) and related species. 

G. atrovircns n. sp., on red gum ( Liquid- 
ambar styraciflua L.). 

G. smaragdmum (A. and S.) Sacc., on red gum (Liquidambar styraciflua L.). 

G. rigidum (Pers.) Sacc., on red oak (Quercus rubra L.). 

G. aureum n. sp., on wli te pine (Finns strobus L.). 

G. album (Corda) Sacc., on beech ( Fagus atropnnicea (Marsh) Sndworth). 

Graphium spp. are perhaps best known by the upright, cylindrical, 
occasionally branched fruiting bodies 1 to 3 millimeters in height 
(fig. 3). These are often brown to black in color and bear at the 
tips comparatively large and, in many cases, confluent globules com¬ 
posed of masses of spores embedded in a mucuslike substance. These 
spore masses, though usually cream color, vary somewhat in hue, and 
in some species are tinged with gray, brown, green, yellow, or red. 
While these are the organs of fructification commonly observed, 
other types less conspicuous and bearing the so-called secondary 
conidia have been demonstrated in culture by Hedgeock (19). 



8 Information from the section of timber physics, Forest Products Laboratory, Madison, 
Wis. 





SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 13 

Other fungi mentioned by Hedgcock ( 19 ) as blackening wood are: 
Alternaria tenuis Nees., Stachybotrys altemans Bon., Aspergillus 
niger , Chaetomium sp., Stemonitis sp., Gliocladium sp., IIormoden- 
dron sp., Ilormiscium sp., and Cladosporium sp. The apparent dis¬ 
coloration in these cases is due either to the presence of colored 
hyphae in or upon the surface of the wood or to a luxuriant super¬ 
ficial growth of colored spore masses. In no case is it due to the 
secretion of any pigment which is absorbed by the wood. 

Hedgcock {19) names three other species— Penicillium aureum 
Corda, Penicillium roseum , and a Fusarium sp. formerly included 
under Fusarium roseum —which, due to the secretion of soluble pig¬ 
ments, actually stain the wood red, purple, or yellow, according to 
the alkalinity or acidity of the medium. These stains are superficial, 
however, and readily dress off when the lumber is planed. Many 
other molds grow readily upon green sapwood and give the timber 
a displeasing appearance, though they cause no deterioration in 
the strength of the wood. From the material collected by the writer 
and sent to the Madison laboratory there have been isolated over 40 
distinct species of fungi. With the exception of species of Ceratosto- 
mella and Graphium, together with a species of Fusarium which was 
identified by Dr. Mabel M. Brown, graduate student at the Uni¬ 
versity of Wisconsin, as F. arthrosporioides , this number consists of 
fungi popularly known as molds. The determination of the molds 
was made by Dr. Charles Thom and Miss Margaret B. Church, of 
the Bureau of Chemistry, United States Department of Agriculture. 
They are listed below: 

Aspergillus flavus series. 

Aspergillus niger. 

Aspergillus repens. 

Aspergillus versicolor group. 

Cephalothecium roseum. 

Citromyces sp. 

Cladosporium sp. 

Clonostachys sp. 

Gliocladium sp. 

Haplographium sp. 

Monilia sitoph ila. 

Mucor sp. 

Oidium sp. 

The great variety of genera and species here noted contains many 
earth dwellers and indicates that the molds commonly found upon 
green timber, especially during storage and transit, are for the most 
part soil forms whose spores have by accident fallen upon the 
moist surfaces of the sapwood and there found the conditions favor¬ 
able for development. 

It has generally been supposed that the growth of mold on wood 
is confined mainly to the surface or, at the most, to the superficial 


Penicillium asperulum or puberulum. 
Penicillium brevicaule series. 
Penicillium commune. 

Penicillium divaricatum. 

Penicilliurn lilacinum. 

Penicillium lutcum. 

Penicillium purpurogenum. 

Penicil 1 iu m roqucfort i. 

Penicillium rngulosum. 

Penicillium solitum. 

Syncephalastrum sp. 

Trichoderma sp. 


14 BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. 

layers, perhaps a few cells in thickness. H. Marshall Ward (55), 
however, in connection with certain experiments upon spruce blocks 
which had been artificially infected with PenlcUUum sp., notes that 
the examination of sections from cultures 3 months old showed that 
the hyphae of this fungus had entered the starch-bearing cells in 
the medullary rays of the sapwood and had consumed the starch. 
The hyphae were observed deep in the wood extending from tracheid 
to tracheid through the bordered pits. Miss A. L. Smith (46) notes 
the presence of a dark-brown hyphomycete in decaying timber. This 
mycelium had invaded the woody tissue and had apparently brought 
about a partial destruction of the medullary rays (see also Free¬ 
man, 12). 9 

During a series of experiments by the writer, cultures were taken 
from various points within red-oak blocks 2-J by 2^- by 10 inches 
long which had been cut from green sapwood and then artificially 
infected with 15 different fungi including 13 of the common molds. 10 

The results obtained seem to confirm Ward’s experiments, for posi¬ 
tive mold cultures were secured even from the center of these blocks. 
However, as far as known, the molds do not cause any serious disin¬ 
tegration of the cell walls in green timber and thus do not impair 
the strength of the wood to any appreciable extent. As in the case 
of the blue-stain fungus, it is the stored food within the cells that is 
the object of attack. 

The principal objection to the presence of mold lies in the dis¬ 
coloration due to the masses of mycelium and the luxuriant clusters 
of fruiting bodies which often develop upon green sapwood, and 
sometimes the heartwood, under conditions of high humidity and 
temperature resulting from poor ventilation. However, these super¬ 
ficial growths are readily removed during sanding or planing opera¬ 
tions. In many cases they can be readily brushed off. This is par¬ 
ticularly true of material which has become surface dried. 

An inspection of a carload of moldy timber is quite likely to pro¬ 
duce an impression that is liable to react unfavorably upon the 
shipper. Moreover, the presence of much mold or sap-stain in 
timber indicates the existence of conditions which are favorable to 
the development of decay. Such material, then, should be viewed 
with suspicion, but not of necessity with unfavorable discrimination. 

FACTORS WHICH FAVOR THE GROWTH OF SAP-STAIN AND MOLD 

FUNGI. 

The development of fungi is dependent upon four factors—a sup¬ 
ply of air, containing the essential element oxygen; the requisite 

9 McBeth and Scales (30) list a considerable number of molds that are apparently able 
to destroy cellulose, though they act differently toward different kinds of cellulose, 

10 See page 29 for the list of fungi used in this experiment. 



SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 15 

amount of moisture; a temperature range within certain limits; and 
the necessary food substances. 

Air .—Fungi require oxygen for their growth. This is supplied as 
one of the constituents of ordinary air. Even under storage con¬ 
ditions the supply is ample. Stagnant air containing a considerable 
amount of moisture is favorable to the growth of fungi in the timber, 
in that it prevents the drying of the wood. Timber entirely sub¬ 
merged in water is practically immune from fungous attacks, since 
the supply of oxygen is cut off. 

Moisture .—The extent of the growth of sap-stain and mold fungi 
is largely dependent upon the amount of moisture present in the 
substratum. This moisture content in green timbers of different 
species as well as in the sapwood and heartwood of a particular 
species may vary considerably. Thus, according to Tiemann (51, 
p. 106; 33, tables), the green sapwood of conifers may contain from 
100 to 150 per cent moisture, 11 while the heartwood, probably being 
near its fiber saturation point, contains about 30 per cent. In the case 
of the hardwoods, both heartwood and sapwood may contain from 
60 to over 200 per cent moisture. Frequently, however, there is pres¬ 
ent a greater quantity of free water in the sapwood than in the heart- 
wood (Tiemann, 51). In air-dried timber the amount of moisture 
may be reduced to anywhere from 8 to 18 per cent, according to the 
climate. In kiln-dried material it may be reduced to 3 to 15 per 
cent moisture, depending upon requirement and uses. This will 
explain why mold and sap-stain, so frequently found in green timber, 
are absent in thoroughly air-seasoned or kiln-dried stock. Air cur¬ 
rents will often surface-dry the timber to an extent that will make 
it practically impossible for fungi to grow thereon. 

The relative quantities of water and air found in the wood, accord¬ 
ing to Yon Schrenk (1$), are the most important factors in the con¬ 
trol of the rate of growth and spread of the sap-stain fungus. He 
cites Munch’s experiments (32) on artificially inoculated pine blocks, 12 
differing only in the relative amounts of contained water and air. 
These experiments seem to indicate that the growth of the fungus is 
inhibited when the normal winter water content of the wood is raised 
to an amount that will insure a consequent reduction in the volume of 
contained air to at least 15 per cent, based on the volume of the fresh 
wood. According to Munch (32) an air content of 42 per cent, 
brought about through a reduction of the normal winter water con- 
tent of the wood, is the optimum for development of the fungus in 
the wood. Munch (31, p. 59-62) states that the sap-stain fungus at- 

11 Unless otherwise stated, all percentages of moisture content are based upon oven- 
dry weight. 

12 The blocks in this case were artificially inoculated with the conidia of Ccratosto- 
mella coerulea. 




16 BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. 

tacks recently felled trees, but does not penetrate deeply, owing to the 
high water content of the wood. He also states that the mycelium of 
the fungus readily penetrates throughout the sapwood of winter- 
felled wood when the loss in water content amounts to 10 to 20 per 
cent. Moreover, the growth in moist wood takes place for the most 
part in the older layers of the sapwood, or those in proximity to the 
heartwood. Finally, Munch concludes that the sap-stain fungus is 
capable of infecting the living tree, thus becoming parasitic, provided 
the fungous spores find entrance to the sapwood through injuries to 
the bark, such as those produced by bark-boring beetles; and that con¬ 
ditions favorable for fungous growth, namely, a reduction in the 
water content and a corresponding increase in the air content of the 
sapwood, are brought about through disturbances in the root s}^stem 
of the tree. 

In this connection certain investigations by Snell (^7) on the rela¬ 
tion of the amount of decay to the density of the wood should be men¬ 
tioned. Five fungi which had been found to cause the rotting of 
structural timber in New England cotton mills were grown upon 
blocks of loblolly-pine sapwood and Sitka spruce. Several series of 
these blocks, each series containing a different percentage of moisture, 
were used in these experiments. The results obtained with loblolly 
pine agreed in the main with those of Munch {32) upon Scotch pine, 
a wood of about the same density. In the case of Sitka spruce, a wood 
of considerably less density, however, it was found that the limits of 
moisture content favorable for fungous growth were raised. In other 
words, “ the values representing the upper limits for decay will vary 
inversely with the 

Temperature .—It has been clearly demonstrated in a number of 
temperature tests 13 upon some of the molds derived from infected 
timber that these fungi grow readily between certain limiting tem¬ 
peratures. Beyond these, they cease to show any signs of activity. 
The optimum temperatures are commonly those which obtain during 
the late spring and summer months in certain parts of the country, 
particularly in the South, i. e., 80° to 85° F. It is probable, how¬ 
ever, that each species has its own characteristic range. 

Food. —Sap-staining fungi and molds have been shown in cultures 
to live upon quite a variety of foods. Being devoid of chlorophyll 
they can not, like the higher plants, manufacture their own food, but 
must depend upon that already available. The medullary rays and 
wood parench}^ma of green sapwood often contain certain starches, 
sugars, and oils which represent the stored food of the tree. These 
are the substances upon which sap-staining fungi probably depend 
for their existence. 

^These tests were conducted at the Forest Froduets Laboratory, Madison, by Mrs. 
Rose Harsch Lynwalter. 


density of the wood.” 




SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 17 

When supplied with the essentials necessary for growth, fungi 
develop rapidly and often reproduce abundantly. Deprived of any 
or all of these factors, however, the vegetative portion, i. e.. mycelium, 
ceases to grow and eventually dies. In some cases, as, for instance, 
certain molds, the spores may retain their vitality for long periods 
under extremely unfavorable circumstances. When favorable con¬ 
ditions return, these spores soon germinate and often develop an 
abundant growth of mycelium within a few days. Fruiting bodies, 
sometimes bearing countless spores, may then make their appearance, 
and the life cycle is repeated. The ideal conditions for growth are 
often to be found in green timber containing a high percentage of 
sapwood when exposed to the stagnant atmosphere of the woods, 
poorly ventilated sheds, warehouses, and cars during warm, sultry, 
or rainy weather. Under such circumstances the sapwood may be¬ 
come thoroughly infected within a few days. Sap-stain may thus 
appear soon after infection with spores or mycelium of the sap-stain 
fungi. Wood-rotting fungi may also get a good hold upon timber 
under such conditions, and symptoms of incipient decay later be¬ 
come apparent (PL I, fig. 6). 

DURABILITY OF STAINED OR MOLDED WOOD. 

Since the blue stain and mold fungi cause little or no dissolution of 
the wood fibers, they do not affect directly the durability of the 
timber. If properly piled and dried, stained or moldy wood stock 
free from decay should not deteriorate further from the action of 
the fungi. However, the conditions which favor the development 
of sap-stain, mold, and sap-rot are much the same, namely, the 
presence of spores or mycelium of the particular fungi capable of 
producing these defects in wood, a substratum containing the 
requisite food material, moisture, and a high relative humidity (75 
to 100 per cent), a temperature of 70° to 100° F., and a lack of circu¬ 
lation of the air, or stagnation, which retards or prevents the proper 
drying of the timber. There seems to exist among many lumbermen 
a false notion that mold and sap-stain represent early stages in the 
development of sap-rot, or “ dote,” as it is commonly called. While 
the presence of an abundant growth of mold or sap-stain in green 
stock indicates conditions which are likely to favor the growth of 
rot, it is well known that the rot is caused by a distinct group of 
true wood-destroying fungi which develop independently. 

Molds in general develop rapidly. Hence, they may be often 
found growing profusely on green timber already infected with rot- 
producing fungi long before the latter have exhibited any notice¬ 
able evidence of their presence. It is possible, however, for wood 
destroyers to infect and bring about the disintegration of wood which 
contains no trace of mold or any other organisms. 

75579°—22-3 



18 BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. 

LOSSES DUE TO SAP-STAIN OR MOLD. 

INSANITARY PRACTICES IN THE HANDLING OF GREEN WOOD STOCK. 

As a result of investigations in the woods, inspections of many car¬ 
loads of green timber and dimension stock upon arrival at the mill, 
examinations of green and seasoned manufactured stock upon ar¬ 
rival at the vehicle factory, and talks with practical millmen and 
lumbermen, the writer is convinced that a considerable amount of 
the damage to vehicle stock, due to fungi, is brought about through 
the use of infected raw material. Many of the infections take place 
in the woods, as a result of insanitary practices in the handling of 
logs, bolts, and split billets. In many instances, during warm and 
humid weather logs and bolts have been allowed to lie in the woods 
for weeks. Under such conditions sap-stain is almost certain to fol¬ 
low. Moreover, the liability to attack by wood-destroying fungi is 
greatly increased. 

Split billets, instead of being cross piled on dry foundations, are 
sometimes thrown carelessly about the stump and left until a con¬ 
venient time for hauling arrives. Under favorable circumstances it 
takes but a few days for certain fungi to gain a good hold on such 
stock, and unless later checked or destroyed by some process such as 
kiln drying, they may produce a permanent stain or decay in the 
sapwood. 

It is quite probable that a serious shortage pf cars suitable for 
handling the logs, bolts, and billets may prevent at times the rapid 
movement of raw stock to the mills. This results in the accumula¬ 
tion of material in the woods and railroad yards and contributes to 
conditions in many cases favorable to the development of the fungi. 
Frequently box cars are used where in normal times the more open 
and consequently better ventilated types of car would be employed. 

Failure to observe proper measures during storage, such as the 
use of dry foundations for logs and bolts, the cross piling or strip¬ 
ping of billets on dry foundations sufficiently high to give suitable 
ventilation from beneath, and the storage of stock in properly venti¬ 
lated sheds, has furnished conditions suitable for the development 
of mold, sap-stain, and decay in such material. 

A few millmen seem to have the mistaken idea that an abundant 
growth of mold on green stock serves to protect it from checking by 
preventing evaporation from the surface of the wood and actually 
absorbing, or possibly condensing, moisture from the surrounding 
atmosphere and then transmitting it to the wood. The fungus de¬ 
rives its moisture from the wood, not the air. Its presence, however, 
often indicates a high humidity in the immediate vicinity, a condition 
which prevents the drying of the wood and thus favors the growth 
of fungi. It is quite probable that the phenomenon known as gutta- 


SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 19 

tion, i. e., the collection of minute drops of excreted water upon the 
fungous growth, is responsible for the misconception. 

In some instances split billets upon being unloaded from the cars 
are thrown in a pile beside the track, sometimes upon damp soil, there 
to remain for perhaps a month or until opportunity can be found for 
removal to storage sheds. Losses due to fungi are a natural conse¬ 
quence of such treatment. 

It has taken time for those unaccustomed to the handling of green 
stock to work out satisfactory methods which would provide proper 
ventilation of dimension, sawed, or turned stock during transit. 
Meantime, many shipments have been seriously damaged. Of the 
different forms of stock, the sawed billet, the rim strip, and plank 
have given the most trouble. Losses are not confined to such stock, 
however, for turned spokes and hubs, unless properly safeguarded 
during transit, are liable to stain and mold. 

Sawed billets often arrive at the factorv in a badly stained con- 
dition. It is probable that material containing fungous infections 
sometimes finds its way into their manufacture. The squared surfaces 
lend themselves to close piling and thus to the formation of masses 
wherein sufficient ventilation is impossible. Rim strips also frequently 
become badly stained while in transit, as a result of the same causes, 
together with the fact that some manufacturers require such stock 
to be close piled in closed box cars and even sprayed with water to 
prevent checking. It is unfortunate that the conditions necessary 
for the prevention of checking in green stock are as a general rule 
favorable to the growth of fungi, and vice versa. 

ECONOMIC IMPORTANCE. 

The presence of much sap-stain and even mold in timber is con¬ 
sidered by some lumbermen as a defect. Therefore, degrading of 
material thus affected, with consequent loss in monetary value, may 
result. Such unfavorable discrimination is due to the notion that 
stained or moldy material is not as sound as clear stock. In the case 
of molds, it is an easy matter to remove the surface blemish by the 
simple process of sanding or planing. With sap-stain, however, the 
removal of the discoloration depends entirely upon the depth to which 
the mycelium has penetrated. In some cases the stain may extend 
to the heartwood. It is evident that it can not under such circum¬ 
stances be removed by the processes referred to. 

The presence of much stain will prevent the use of timber for pur¬ 
poses where color, texture, and clearness of grain are of prime 
importance. Basket and box veneer, interior finish, flooring, and 
furniture stock which are to have no protecting coat of paint must 
be free from stain. Discrimination, however, should not be made 


20 


BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. 


against sap-stained or moldy stock that is to be covered, provided 
there is no incipient decay associated with it. 

The reduction in the value of stained lumber sometimes amounts 
to $2 or more per 1,000 feet, board measure, and perhaps one-fourth 
of the annual mill cut of the United States is attacked. In one year 
it was estimated that the total losses from sap-stain amounted to be¬ 
tween 8 and 9 million dollars (Weiss, 56 ; Weiss and Barnum, 57 ; see 
also Pratt, 3If ). The amount in any locality, however, depends upon 
the climate, the season, and several other factors. 

Weather conditions have a marked influence upon the amount of 
damage to freshly cut timber in the woods or to green stock in storage 
and in transit. During warm and moist Aveather such stock Avill 
sometimes stain badly and in a short time, unless it is properly safe¬ 
guarded. This, of course, i's due to the fact that the Avarm and humid 
conditions stimulate the development of the fungi. It folloAvs, then, 
that the greater losses from sap-stain, sap-rot, or mold should be ex¬ 
pected during the Avarmer months, and especially during those 
months in which both high temperatures and high humidity nor¬ 
mally prevail. As a matter of fact, this is the case. In the months 
of April, May, June, July, and sometimes August and even Septem¬ 
ber, depending upon climatic conditions, the greatest damage occurs. 
In the South, OAving to the preA'ailing high temperatures and relative 
humidities, the losses are often extremely severe. The greatest losses 
occur in loAv-grade coniferous lumber, especially the southern pines, 
owing partly to the high percentage of sapwood and partly to the 
fact that the low-grade lumber is seldom kiln dried, but is stacked 
in the yard to air season. Under such circumstances, unless unusual 
precautions are obseiwed, it is A T ery liable to the attacks of the sap- 
stain fungi. 

From replies to the questionnaires sent out by the Avood-stock com¬ 
mittee to contractors and producers of Avood stock regarding sap- 
stain and mold in vehicle stock and from the data derh r ed from the 
personal investigations of the Avriter, it Avas learned that these losses 
are dependent largely upon the manner in which the stock is piled in 
the cars and sheds during transit or storage. The losses average less 
than 10 per cent, but may reach from 25 tS 75 per cent. The writer 
Avas informed that because of such damage to green spokes during 
the summer of 1918, sometimes as many as 50 per cent in a carload 
lot Avere culled. When turned spokes Avere selling at $150 per 1,000 
feet b. m., the loss on a carload containing perhaps 12,000 escort 
spokes, 2| by 24 by 27 inches, Avas eAddently considerable, perhaps 
amounting to hundreds of dollars. One firm reported that it had 
knowledge of entire carloads being destroyed. In some instances 
cars had gone astray and had finally reached their proper destina- 


SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 


21 


tion after one or two months on the road. Losses in those cases were 
often practically complete. Sixteen different firms reported that 
for the year 1917 their individual losses due to “ heating in transit,’ 7 
as staining is sometimes explained by lumbermen, varied from $100 
to $5,000. One company reported the losses as varying from $25,000 
to over $75,000 in different years. 14 

CONTROL MEASURES. 

A great many attempts have been made to devise measures for 
the control of sap-stain and mold in green timber. With the excep¬ 
tion of kiln drying, however, none of these has proved entirely satis¬ 
factory. When tried under circumstances unfavorable to the growth 
of fungi, some of these measures have met with considerable success, 
but when put to the test under conditions which stimulate fungous 
development, they have often failed. For the most part they have 
been prophylactic rather than curative in nature. However, it is 
believed that many of the following measures, although not entirely 
effective, will assist materially in reducing losses due to sap-stain, 
mold, and incipient decay in green stock. 

HANDLING IN THE WOODS. 

AUTUMN AND WINTER CUTTING. 

Many lumbermen (15) think that, where possible, timber should be 
cut in the autumn and winter. While this is probably true, the reason 
often given is incorrect. The statement is usually made that winter 
cutting is better because the “ sap is down.” It has been shown by T. 
Hartig (33, tables; Janka, 26) that during the spring when the growth 
is most active the tree sometimes contains less water than in the winter. 
It is probable that the changes in moisture content which do take place 
are confined mainly to the sapwood. It is true that the movement of 
sap is much more rapid at the time of active growth and that there 
are important chemical changes which take place therein, during the 
different seasons of the year. In the winter, insoluble starches and 
gums are stored in the sapwood. During the spring these are 
changed to soluble sugars and are borne through the living tissues. 
The sapwood of summer-cut logs, therefore, contains soluble foods 
which render it extremely susceptible to attacks by fungi during the 
warm months when these organisms are most active. Winter-cut logs, 
on the other hand, have an opportunity to season under conditions 
less favorable for fungous growth and by the time warm weather 

14 National Implement and Vehicle Association and other Vehicle and Vehicle Parts 
Manufacturers. Information Division of the Wagon and \ ehicle Committee and the 
Wheel Manufacturers’ War Service Committee. Wood Stock Committee. Sap-stain and 
mold in transit. Nat. Implement and Vehicle Assoc., etc., Bui. 30, 5 p. 1918. A. B. 
Thielens, chairman. Typewritten. 




22 


BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. 


arrives will have dried to a decree which will render them less sus¬ 
ceptible to fungi (Roth, 55, p. 57). 

In the bottom lands of the South, however, autumn and winter 
cutting may not always be feasible owing to the wet and muddy 
conditions then prevailing, which make hauling difficult, if not im¬ 
possible. 

Incidentally, leaf seasoning (Tiemann, 51), i. e., girdling trees 
while in full leaf and then allowing them to remain, often for years 
or until the leaves have entirely shriveled up, with the idea, that much 
of the free water in the sap wood will be drawn off by transpiration 
through the leaf surfaces and thus prevent sap-stain, does not seem to 
be practiced in the regions visited by the writer. Although this 
method is said to be common in the seasoning of teak in India and 
has been advocated by some as applicable to gum in this country, yet 
it does not seem to meet with general approval, because it exposes 
the timber to the ravages of insects and to fungi causing decay. 

RAPID HAULING. 

One of the precautionary measures to be observed, especially dur¬ 
ing the late spring and summer, is that of hauling timber immedi¬ 
ately after felling. Raw stock can not be gotten out of the w T oods 
and to the saw too rapidly. It is possible for fungous infections to 
take place at all times, of the year on the exposed surfaces of freshly 
cut timber. These develop more rapidly, however, during warm, 
humid weather, and especially under the conditions which obtain in 
the woods. 

STORAGE IN THE WOODS. 

If it is found necessary to allow logs and bolts to remain in the 
woods, they should be so separated that the ends are left several 
inches apart. If the sawed ends remain in contact, fungi are liable 
to develop between them. Some have recommended that logs that 
are to remain in the woods during the summer be painted on the 
Exposed ends with creosote (Yon Schrenk ,' 1$). It has been con¬ 
sidered advantageous by some (Yon Schrenk, 1$\ see also Hartig, 18) 
to remove the bark from logs that must of necessity be left in the 
woods for an extended period. Advocates of such treatment state 
that the peeled surfaces soon become air-dried and consequently 
provide insufficient moisture for the germination of any fungous 
spores that may fall thereon. In order to keep such logs off the 
damp ground and thus assist in the air-drying process measures must 
be taken to provide some sort of temporary foundation free from 
stain, mold, or rot. 

When it becomes necessary to store split billets in the woods, they 
should be piled with only two billets in a course and should rest upon 


SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 


23 



a foundation located on dry ground and consisting, where possible, 
of billets of split heartwood free from rot. 

HANDLING RAW STOCK IN TRANSIT. 

TYPES OF CARS. 

In shipping green stock to be used in the manufacture of vehicles, 
etc., the following types of cars have been preferred: 

Flat cars-logs (fig. 4). 

Gondolas or stock cars____Jbolts (fig. 5). 

Stock or vegetable cars-split billets or dimension stock. 

Ventilated box cars---lumber or dimension stock. 


Fig. 4.—Unloading logs from a flat car. This is the type of car usually used for the 

shipment of logs. 

PROVISIONS FOR THE PROPER VENTILATION OF STOCK IN TRANSIT. 

Well-ventilated types of cars should be selected where possible, if 
staining and molding are to be prevented (figs. 4 to 10). Prepara¬ 
tory to use, these cars should be thoroughly swept free from 
rubbish, damp sawdust, lime, or manure. In the case of box cars, 
it is important that the roofs be carefully inspected to make sure 
that they are water-tight. If it becomes necessary to use box cars 
for the transportation of split billets during the late spring and, 
summer months, it is suggested that the billets be ricked and that 
strips or occasional crossers of the same stock at intervals of 12 to 
16 inches be used to assist in the ventilation of the pile. Side doors 
should be open and both doorways boarded up, leaving at least 14- 
inch spaces between the boards. If box cars are equipped with small 








24 


BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. 



end doors of the ventilating type, these doors should be left open and 
the doorways cleated to prevent the stock from working out during 
transit. Lumber shipped in box cars must be stripped. 

HANDLING HAW STOCK IN THE YARDS. 

STORAGE OF LOGS AND BOLTS. 

When piling or cording logs and bolts in the yard for storage, it is 
important that they be kept off the ground by the use of clean skids 
or permanent foundations of seasoned fungus-free planks, stone, or 
cement. Such foundations should be placed on well-drained soil 
free from underbrush or weeds that might interfere with proper ven¬ 
tilation from beneath. 


Fig. 5.—Bolts loaded in a gondola car. Gondolas, stock, or vegetable cars are best 
adapted to the transportation of this type of raw stock. 

STORAGE OF BILLETS. 

Billets that are not turned at once should be stored upon dry 
foundations and in properly ventilated sheds (fig. 11). When suf¬ 
ficient storage space is available, the method of piling used by one 
of the large wheel manufacturers in the North, shown in figure 12, 
is recommended. 

STORAGE OF GREEN LUMBER. 

The methods of piling lumber are pretty well understood and need 
little explanation here (7). 15 In general, it is well to select a location 


10 For information concerning this point, the reader is referred to Bulletin No. 552, 
United States Department of Agriculture (7), copies of which may be obtained from the 
Superintendent of Documents, Government Printing Office, Washington, D. C., at 10 cents 
per copy. 






SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 


25 



on well-drained soil free from weeds and one which will allow the 
prevailing winds to blow through the sides rather than upon the ends 
of the stacks. 

Care should be taken to provide suitable foundations consisting of 
metal or well-seasoned heart stock, preferably creosoted and resting 
upon piers of creosoted wood or, better, of stone, brick, concrete, or 
metal. All foundations should be sufficiently high to allow for 
ventilation vertically through the stacks. Moreover, there should be 
ample space between 
the stacks to permit 
a free circulation of 
the air around them. 

Finally, it is impor¬ 
tant t h.a t narrow 
strips, perhaps 1 inch 
wide and at least 1 
inch thick, of well- 
seasoned, kiln-dried, 
or chemically treated 
wood be used between 
all courses and that 
they be carefully 
placed in vertical 
alignment to prevent 
warping of the 
stock. 16 


HANDLING AT THE MILL. 


EARLY MANUFACTURE. 

Logs, bolts, and - -—:——--- ^ ■ / l 

split billets should be Fig. 6.—Bolts piled in a box car. Note the debris on the 

sawed into dimension fl001 of the car ‘ Bo,ts are 9keiy to suffer from fungous 

attacks when shipped in box cars with the doors closed. 

stock or planks and 

manufactured as soon as possible. This will do much toward safe¬ 
guarding the material by reducing the time in storage. 


AIR SEASONING. 

Provided kilns are not available, the dimension stock should be 
seasoned from six months to a year or more, depending upon the 


10 The general sanitation of lumber yards and the proper methods to be observed in 
the piling of timber to prevent or reduce losses in storage due to fungi, together with a 
consideration of the more common rot-producing organisms, are clearly described by 
Humphrey ( 22 ), in Bulletin No. 510, United States Department of Agriculture. Copies 
may be obtained from the Superintendent of Documents, Government Printing Office, 
Washington, D. C., at 20 cents per copy. 

75579°—22 


4 








26 


BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. 



17 The reader is again referred to Department Bulletin No. 552 (7) for information con¬ 
cerning the seasoning of wood. 


size and kind of material. 17 When sufficiently dry, shipments in 
closed box cars will suffer little or no loss from sap-stain or mold. 
In all cases where air seasoning is resorted to, unless great care is 
exercised in providing for ample circulation of air through the stock 
by such means as open piling, fungous and insect troubles are likely 
to develop. It is absolutely necessary to strip or cross pile the stock 
upon dry foundations. For purposes of stripping, kiln-dried or 

chemically treated strips 1 inch wide and at least 1 inch thick should 

be used between 


courses. All sheds 
for the storage of 
this material should 
be drv and well ven- 

•s 

tilated. 


KILN DRYING. 


By far the most 
effective and quickest 
method of treating 
green stock, as a pro¬ 
phylactic measure, to 
destroy fungi or in¬ 
sects and to reduce 
shipping weight, is 
to subject the ma¬ 
terial to proper kiln 
drying. When pro- 

Fig. 7.—Split billets piled in a box car. When occasional t 

billets are used as crossers and the doors of the car are GUCCIS are equipped. 

cleated open this type of spoke stock suffers but little with. Or have access 
while in transit. . 

to, modern kilns op¬ 
erated on a scientific basis and are so situated that stock can be 
moved rapidly, less concern need be given to fungous troubles. Kiln- 
dried spokes can be bundled or close piled in dry warehouses or in 
ordinary box cars and shipped without loss. 

Material kiln dried directly from the saw has been shown to be 
just as good as air-seasoned stock (Tiemann, 51 , p. 300) and in many 
cases much better as far as strength, toughness, and freedom from 
defects are concerned. Moreover, the time necessary for seasoning 
can often be reduced from one year to three weeks or from three to 
five years to as many months. 








SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 


27 


Kiln drying reduces shipping weight; makes the lumber fit for 
almost immediate use; eliminates or reduces losses due to insects, 18 
or to checking, rotting, staining, or molding; improves the quality 
of the lumber; reduces the amount of yard space; and saves the 
tying up of capital and carrying costs (Tiemann, 57, p. 4, 5). 

It is possible that where several producers are located within a 
few miles of one another, a battery of modern dry kilns, operated 
according to the most approved methods (possibly on the community 
plan) might solve the problem of cost of installation and operation. 

In dry kilns, stripping or cross piling the stock and providing 
means to prevent stagnation of the confined air are absolutely neces¬ 
sary if the develop¬ 
ment of mold is to be 
avoided. The water 
spray kiln devised at 
the Forests Products 
Laboratory represents 
one of the latest de¬ 
velopments in the tem¬ 
perature and humidity- 
controlled type of 
kiln. 19 

During the first few 
weeks of kiln drying, 
when the humidity is 
high and the tempera¬ 
ture ranges from 80° 
to 105° F., an abundant 
growth of white mycelium occasionally forms between the courses 
and interferes more or less with the circulation of the air in the kiln. 
This is due to the presence of mold fungi, and it usually indicates 
stagnation in the kiln (PI. I, fig. 4). Steaming for one hour at a 
temperature of 160° to 180° F. has been found effective in destroy¬ 
ing or at least checking the growth of this mold (Tiemann (57), 
p. 187). 



Fig. 8. —Split billets loosely piled in tbe areaway between 
the doors of a box car. The doorways are loosely 
boarded up to allow for ventilation of the car and at 
the same time prevent the stock from working out 
while in transit. 


18 Towder-post beetles, however, are said to cause considerable damage at times in 
seasoned stock ; in fact, these beetles do not work in green stock. 

19 A complete description of this kiln is given in Bulletin No. 509, United States Depart¬ 
ment of Agriculture (52), a copy of which may be procured from the Superintendent of 
Documents, Government Printing Office, Washington, D. C., for 5 cents. Further infor¬ 
mation concerning the design and installation of this kiln is given in Bulletin No. 894, 
United States Department of Agriculture ( 50 ), to be procured from the same source at 
10 cents a copy. 










28 BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. 


STEAMING GREEN STOCK AS A CONTROL MEASURE. 

METHODS COMMERCIALLY EMPLOYED. 

Steaming certain kinds of stock (green gum lumber, birch hubs, 
spokes, and sawed felloes of red or white oak) is sometimes resorted 
to as a means of reducing shipping weight by hastening drying or 
to even up the color and reveal defects in the wood. 

In the steaming of green gum lumber a large steel tank, or pre- 
parator, is employed. The lumber loaded upon trucks is run into 
this preparator and steamed for perhaps 15 to 30 minutes at pres¬ 
sures of 20 to 30 pounds (figs. 13 and 14). Provided this lumber is 

then carefully open 
piled, it remains clean. 
When close piled or 
when exposed to ad¬ 
verse weather condi¬ 
tions, however, it may 
mold almost as readily 
as untreated green 
lumber. 

Hubs, sawed felloes, 
and turned spokes 
green from the saw are 
sometimes steamed at 
atmospheric pressure. 
At one plant visited, 
green birch hubs were 
stacked in large cement 
boxes and subjected to 
exhaust steam for 24 
to 36 hours, depending 
upon the size of the 
hub. At the end of that time the steam was shut off and the hubs 
were allowed to cool for perhaps 10 hours. The hubs were then 
carried to a ventilated warehouse and stacked, zigzag fashion, to 
provide for ample circulation of the air through the inside as w^ell 
as around them. In this manner an even drying was secured. Two 
to three weeks was considered a sufficient length of time for the 
necessary air drying previous to shipping. During the warmer 
months, stock cars were used as means of transportation. 

The steaming of gum and birch is a comparatively simple process. 
But in the case of woods that check readily, such as oak, this treat¬ 
ment requires considerable care. 





Fig. 9.—A box car loaded with split billets upon its 
arrival at the spoke mill. The method of loosely 
boarding the doorway, as shown in figure 8. is prefer¬ 
able in that there is less danger of the stock working 
out while in transit. When, however, the masses of 
billets are held in position by supports, or when ver¬ 
tical boards are nailed a few inches back of the cleats, 
this method may be used. Both provide for the venti¬ 
lation of the stock. 




































SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 


29 


THE EXPERIMENTAL STEAMING OF RED-OAK AND WHITE-OAK BLOCKS AT THE LABORATORY OF 

FOREST PATHOLOGY, MADISON, WIS. 



During the spring of 1919 the writer performed several series of 
experiments at the Madison laboratory to determine the efficiency of 
steam at atmospheric pressure in destroying mold and sap-stain fungi 
in artificially infected red or white oak blocks 2J by 2^ by 10 inches. 
Incidentally the rate of drying and the amount of checking were 
noted in connection 


with the steaming. 

The blocks were 
sawed from the sap- 
wood of summer-cut 
logs, weighed, and 
then sprayed with a 
water suspension of 
spores t a k e n from 
cultures of mold 
fungi originally de¬ 
rived from infected 
material sent in bv 
the writer. A list 
of the fungi used in 
these experiments 
follows: 

Aspergillus flavus. 
Aspergillus niger. 

Cep halo th ecium roseum. 
Ceratostomella sp. 
Citromyces sp. 

Graphium sp. 

Monilia sitophila. 

Mucor sp. 

Penicillium asperulum. 
Penicillium divarica t urn . 


Penicillium lu teum. 


Pen icillin in p i n op hi l u m . 
Penicillium rugulosum. 
Syncephalastrum sp. 
Trichoderma sp. 


Fig. 10.—Square billets close piled in a box car. This type 
of raw stock suffers considerably when piled in the 
manner shown here. Stripping or cross piling while in 
transit or storage is essential if losses from fungi are 
to be avoided. 


The sprayed blocks were then placed in a tile chamber, which 
served as an incubator. After several weeks in this chamber, where 
an average relative humidity of 95 per cent and an average tempera¬ 
ture of 70° F. prevailed, the blocks became well infected and de¬ 
veloped countless numbers of the fruiting bodies peculiar to the fungi 
mentioned above (PI. II, fig. 1). 





30 


BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. 



A steam box was constructed of cypress, equipped with thermome¬ 
ters, dew-point apparatus, and manometer and connected with the 
main which supplies steam to the laboratory greenhouse (figs. 15 and 
16). By means of suitable reducing valves in the connecting pipes 
it was possible to control the steam pressure in the box; hence, the 

exact conditions to 
which the blocks 
were subjected could 
be readilv determ- 
ined. Steam at at¬ 
mospheric pressure 
onlv was used. 

Previous to steam¬ 
ing, the blocks were 
again weighed. 
They were then 
close piled or strip¬ 
ped in groups of 25 
in the steam box and 
steamed for differ¬ 
ent lengths of time. 
At the end of the 
steaming period, 
some of the lots were 
allowed to cool for a 
certain time and then 
reweighed. Others 
were weighed imme¬ 
diately. Xearly all 
were put in a small 
ventilated box in the 
open and allowed to 
air-dry for several 
weeks. Some, how¬ 
ever, were placed in 
a closed shed for 
four weeks, and still 
others were taken 
from the steam box, weighed, and placed directly in the tile chamber. 
Some lots were stripped; others were close piled. An interval of at 
least 3 inches was maintained between adjacent piles. 

After the preliminary seasoning mentioned above, a number of the 
blocks were returned to the tile chamber for incubation. This was 
done for the purpose of subjecting the blocks to the conditions exist¬ 
ing in box cars and poorly A^entilated warehouses during warm and 


Fig. 11.—Stacking sawed billets in an open shed. It will 
be observed that the billets at the extreme right are 
cross piled, while those in the center are close piled. 
The former method of piling insures a better ventila¬ 
tion of the stack, provided intervals of at least 1 inch 
are left between the adjacent billets of a course. In 
the case of the cross-piled billets shown here this pro¬ 
vision was not made. 



SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 


31 


sultry weather. The tile chamber, when given a preliminary treat¬ 
ment, which consisted of intermittent steaming for three successive 
days to reduce the amount of viable fungous growth therein, pro¬ 
vided these conditions admirably. In this chamber the temperature 
was maintained at an average of 85° F., while the relative humidity 
varied from TO to 95 per cent. At the end of four weeks in the tile 
chamber the blocks were removed and their condition with respect 
to molding noted. 

The following observations were made from several series of exper¬ 
iments : 


The amount of drying which took place in the steam box was comparatively 
slight. This seemed to depend, however, upon the relative moisture content of the 
wood previous to steam- 

C 


ing. Green blocks usu¬ 
ally lost, while partly 
seasoned blocks often 
gained in weight. 

Beyond a certain 
length of time, dependent 
upon the moisture con¬ 
tent of the wood and 
the surface area of the 
blocks in relation to vol¬ 
ume, there seemed to be 
little gained, in so far as 
the reduction in weight 
was concerned, by con¬ 
tinued steaming. Six or 
nine hours’ s t e a m i n g 
seemed to be no more 
efficient than three hours 
in the case of the 2i by 
2\ by 10 inch blocks. 


. ~—i r i 






KT&T2¥S 


) [ 


ZL 




. . r._ , 

jSSESS 

~r- 


. __ ._ i' r i 


c 


/ 75 > «<SV Vfrx 

JZ223 Ea mm{2Zn E22& £2221£221 fuZZ. 


3 


Pig. 12.— Diagram illustrating one method of stacking 
green split billets. This method is used by one of the 
large wheel factories of the North. When ample storage 
space in well-ventilated sheds is available, this method 
is recommended. 


Steamed blocks subsequently dried more rapidly than those that were simply 


air-dried. 

Open piling or stripping in the steam box was preferable, in that it per¬ 
mitted a better circulation of the steam in the box and thus insured a more 
uniform treatment of the blocks. 

The amount of checking varied in the several lots when steamed under the 
same conditions. This may have been due to the fact that the blocks differed 
considerably in the relative proportion of sapwood and heartwood present. 

The greatest amount of checking occurred in those lots that were subjected 
to rapid cooling and surface drying by exposure to air currents from open doors 
and ventilators. Blocks allowed to cool in the steam box with doors closed 
seemed to suffer least in this regard. Slow cooling was, in some cases, brought 
about by opening a small hatch in the roof of the steam box at the conclusion 
of the steaming period. 

The total amount of checking which had taken place in the steamed blocks, 
both during the steaming process and the subsequent, period of air seasoning, 
extending over four months, exceeded but little that noted in those blocks which 
had been simply air seasoned for the same length of time. 

Steaming seemed to be effective in killing the fungi in the infected blocks 
when employed for a period of three hours. Cultures taken fi oiu ^ arious points 








































































32 


BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. 


in or upon the blocks by means of a sterile scalpel and needle gave no growth, 
while cultures taken from check blocks which had not been steamed gave positive 
results in every case. 

Steamed material, unless open piled under conditions which insured an ample 
supply of circulating air, molded almost as readily as green stock. 

Steamed blocks that were given a month’s air drying subsequent to steaming 
and previous to storage under the extreme conditions that prevailed in the tile 
chamber showed a little more resistance to the invasion of fungi than those 
blocks that were placed in the tile chamber immediately after steaming. 

It is quite probable that the steam treatment of wood stock, fol¬ 
lowed immediately by prolonged submersion of the material in some 
of the antiseptic solutions to be described later, might prove to be a 



Fig. 13.—Boards of red gum loaded on a truck and ready to be rolled into the prepa- 

rator (shown in fig. 14). 

fairly effective method for the control of fungi in infected stock. 
This treatment might be applied to special classes of wood stock 
where the margin of profit would justify the extra cost. 

THE CHEMICAL TREATMENT OF GREEN WOOD STOCK. 

Many attempts have been made to find some chemical compound 
or mixture that, when applied as a dip, will control sap-stain and 
mold in green timber. A great many substances have been tried, but 
none have proved entirely satisfactory. Under conditions not par¬ 
ticularly favorable to the growth of fungi, several have met with 
considerable success. On the other hand, if the conditions were 
stimulating to fungous growth, the same substances often failed. 
Some treatments depend for their efficiency upon the neutralization 
of the acids in the wood and, at the same time, the establishment of 























SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 


33 


alkaline conditions. To this group belong sodium carbonate, sodium 
bicarbonate, sodium hydroxid, lime, and borax. Others are intended 
to poison the food of the fungi, and comprise such compounds and 
mixtures as mercuric chlorid, copper sulphate, sodium fluorid, creo¬ 
sote, and many other substances. 

Toxicity tests (Humphrey and Fleming, ^) 20 conducted at the 
Madison laboratory upon a few molds commonly occurring upon 
infected timber, as well as upon several wood-destroying fungi, have 
clearly demonstrated that when the entire culture medium is perme¬ 
ated with these and many other preservatives, often in very small 
amounts, the growth of the fungus can be readily inhibited. Hence, 



Fig. 14.—Preparator used for the commercial steaming of red-gum lumber at one of 

the mills in Arkansas. 


if wood be thoroughly impregnated with a solution of one of these 
common preservatives it will be protected from decay as well as from 
sap-stain and mold. 

This is quite possible in the case of thoroughly seasoned timber 
impregnated with preservatives by subjection to high pressure in 
closed retorts. The penetration of green timber by cold solutions 
of salts in an open tank or by the brush treatment, however, is ex¬ 
tremely slight. 21 Tests made by the writer for the presence of cop¬ 
per in the interior of § by f by 1J inch blocks sawed from the green 


20 Information also obtained from unpublished reports of toxicity experiments per¬ 
formed by Miss C. Audrey Richards at the Laboratory of Forest Pathology, Madison, Wis. 

21 For a description of the pressure, open-tank, and brush treatments, the reader is re¬ 
ferred to Forest Service Bulletin No. 78 (45) and to Farmers’ Bulletin 744 ( 25 ), U. S. 
Department of Agriculture. 







34 BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. 

sapwood of red oak and then dipped for 10 seconds in solutions of 
copper nitrate and copper sulphate at ordinary temperature showed 
that these solutions had penetrated the ends of the blocks for a dis¬ 
tance less than 5 millimeters (one-fifth of an inch) and scarcely a 
measurable amount in the case of the tangential or radial surfaces. 
It is evident, then, that whatever value there is in the use of cold 
dipping solutions lies entirely in the superficial coating of the pre¬ 
servative left upon the wood. Provided this is not brushed off or 
washed off by rain, it may inhibit or prevent the germination of 
fungous spores which happen to fall upon such surfaces. Hot solu- 



Fig. 15.—Steam box of cypress used in the experimental steaming of red-oak and 

white-oak blocks at the Madison laboratory. 


tions, in that they tend to prevent the collection of bubbles of air 
upon the surface of the wood, probably give a more uniform distribu¬ 
tion of the preservative over the dipped material. As far as pene¬ 
tration is concerned, however, it is doubtful whether the hot solu¬ 
tions, as ordinarily employed, possess any very great advantages. A 
slightly increased penetration may be secured by first subjecting the 
stock to a thorough steaming or by heating it for some time in a hot 
solution of the preservatives, as in the open-tank process. The air 
within the cavities of the wood is thereby expanded, and some es¬ 
capes. Provided the steamed or hot wood is at once transferred to 
a cold solution of the preservative and there allowed to remain till 















SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 


35 



cool, an amount, approximately equal to the original volume of the 
escaped air, will be forced into the wood, d his is a slow process, 
however, and therefore somewhat expensive. 

The rate of evaporation of the liquid, in the case of hot solutions, 
is much greater than in cold solutions; hence, it becomes necessary to 
take frequent hydrometer readings of the bath and to make the 
proper adjustments in the relative proportions of the solvent and dis¬ 
solved substances in order to maintain a uniform concentration. 

Dipping may be of some value when applied to stock free from 
fungi. In those cases 


where the fungi are 
already in the tim¬ 
ber, however, it is 
doubtful whether 
very much good can 
result from chemical 
dips unless the ma¬ 
terial be subjected 
first to a relatively 
high temperature 
and for a length of 
time sufficient to de- 
strov these organ- 

•s O 

isms. 

The salts used in 
the chemical treat¬ 
ment of lumber are 
likely to vary con¬ 
siderably in strengtli 
and purity. It is 
probable that the 
lack of uniformity 
in the results ob¬ 
tained by different 
investigators when 
employing nominally the same compounds may be traced partly to 
this cause. A few of the preservatives commonly used are de¬ 
scribed here. 


Fig. 16.—Details of the interior of the steam box used in 
the experimental steaming of red-oak and white-oak 
blocks at the Madison laboratory. 


SODIUM CARBONATE AND SODIUM BICARBONATE. 


The substances which have been most frequently employed to pre¬ 
vent sap-stain in lumber are sodium carbonate (commonly in the form 
of soda ash) and sodium bicarbonate (baking soda). Solutions of 
these salts are applied either hot or cold by dipping in an open tank. 
On southern yellow pine, when used in concentrations of 4 to 5 per 
cent sodium carbonate and 5 to 6 per cent sodium bicarbonate, these 








36 BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. 

substances have given more or less satisfactory results (Weiss and 
Barnum, 57). In wet weather, however, it has been found necessary 
practically to double the strength of the solutions. Moreover, both 
sodium carbonate and sodium bicarbonate cause a yellow to brown 
discoloration of the wood. Lumber treated with these preservatives 
must be open piled or it may mold and stain badly during warm, 
humid weather. 

A good grade of sodium carbonate in the form of soda ash should 
contain 58J per cent alkali, while the amount present in sodium bi¬ 
carbonate (baking soda) is about 37 per cent. Solutions of the latter 
are more or less decomposed at temperatures above 158° F., giving off 
carbon dioxid. In a series of laboratory experiments followed by 
practical field tests on southern yellow pine and red gum, Rumbold 
(37) found that the blue-stain fungus is sensitive to alkalis but not 
to acids, that an 8 per cent solution of sodium carbonate is as effec¬ 
tive as an 11 per cent solution of sodium bicarbonate, and that the 
amount necessary to prevent growth varies with the substratum. 
Freshly cut sapwood of southern yellow pine or red gum required 8 
per cent sodium carbonate and 10 per cent sodium bicarbonate solu¬ 
tions under conditions which were especially favorable for the growth 
of the blue-stain fungus. In dry weather a weak solution of the 
alkali (a 5 per cent solution of sodium carbonate and a 4 per cent 
solution of the bicarbonate) kept the yellow pine boards free from 
stain. It was also observed that the spores of the blue-stain fungus 
are more resistant than the mycelium. These experiments seem to 
show that sodium carbonate and sodium bicarbonate possess some 
value as a preventive against sap-stain but that the success attending 
the treatment is largely dependent upon weather conditions. 

SODIUM FLUORID, SODIUM BIFLUORID, AMMONIUM FLUORID. 

Sodium fluorid, which has proved to be very toxic to wood-destroy¬ 
ing fungi (Teesdale, Ifl), has also been tested to determine its 
toxic properties in connection with the blue-stain fungus. Represen¬ 
tatives 22 of the Forest Products Laboratory, working independently 
and in cooperation with certain lumber mills located in Mississippi 
and Louisiana, found that both sodium fluorid and sodium bifluorid 
were effective against sap-stain. The fluorids have an advantage 
over sodium carbonate and sodium bicarbonate in that they do not 
discolor the timber. One of these investigators, in a comparative 
series of experiments with a number of preservatives, including 2J 
per cent sodium fluorid, 2£ per cent sodium bifluorid, and 2J per cent 
ammonium fluorid, found that in the concentrations mentioned these 
salts were fairly effective against sap-stain. The ammonium fluorid, 

n Unpublished reports by Pettigrew and Knowlton in the files of the Forest Products 
Laboratory, Madison, Wis. 



SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 


37 


in addition, seemed to be of some value in controlling mold. How¬ 
ever, bpth of these series of experiments were performed during hot 
and dry weather—conditions unfavorable to fungous growth; hence, 
it is impossible to draw satisfactory conclusions from the results. 

While the fluorids may be effective in controlling decay and, to a 
certain extent, stain-producing organisms, they can not be depended 
upon to prevent molding. 

MERCURIC CHLORID. 

Probably the best antiseptic to prevent sap-stain and mold in green 
wood stock is mercuric chlorid. When used on coniferous woods and 
on many of the hardwoods in concentrations of 0.1 per cent to 1 per 
cent, it has been found to be exceedingly efficient. The addition of 
0.1 to 1 per cent hydrochloric acid is said to increase its stability. 
Mercuric chlorid, however, is extremely poisonous when taken in¬ 
ternally. Many individuals show a marked susceptibility to the 
poison even when applied externally. Moreover, the solutions of 
mercuric chlorid are corrosive to iron, zinc, and many other metals 
commonly employed in dipping vats. For these reasons it can not be 
recommended for general use. 

SOME RESULTS OBTAINED FROM THE USE OF ANTISEPTICS BY VARIOUS INVESTIGATORS. 

It is probable that the efficiency of a given antiseptic varies consid¬ 
erably when applied to woods of different species and at various . 
stages of air seasoning. As stated before, the results are likewise de¬ 
pendent upon climatic conditions. On open-piled boards of shortleaf 
pine in Missouri, Von Schrenk, Bessey, and Spaulding found that 5 
per cent sodium bicarbonate or one-twentieth per cent mercuric 
chlorid gave good results (Hedgcock, 20). On open-piled white pine 
in Wisconsin, the first two investigators found that the solutions giv¬ 
ing the best results were 5 per cent borax and 2.5 per cent sodium bi¬ 
carbonate, while on boards of Norway pine in open piles 5 per cent 
borax, one-twentieth of 1 per cent mercuric chlorid, and 2.5 per cent 
sodium bicarbonate were most effective (Hedgcock, 20). As the re¬ 
sult of experiments on longleaf pine boards in open piles at Bogalusa, 
La., Weiss and Barnum (56, 57) concluded that the most effective 
antiseptics for the control of sap-stain, in that wood at least, are mer¬ 
curic chlorid in concentrations of 0.1 to 1 per cent and sodium bicar¬ 
bonate in strengths varying from 5 to 10 per cent. In these experi¬ 
ments 5 per cent borax gave poor results. 

Hedgcock (20), in connection with certain experiments at Balti¬ 
more, Md., on the prevention of mold and stain in veneer baskets 
made from poplar, sycamore, beech, gum, and maple, found that the 
most effective solutions were 10 per cent sodium carbonate, 6.5 and 
10 per cent sodium bicarbonate, 2.5 per cent sodium bicarbonate plus 



38 


BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. 



0.66 per cent borax and boric acid, 0.20 per cent sulphur plus 0.20 
per cent lime, 0.10 per cent mercuric chlorid plus 0.20 per cent 
hydrochloric acid, 10 per cent potassium (alum), and 0.33 per cent 
phenol salicylate. He concludes that of these substances, 5 to 10 per 
cent sodium bicarbonate is the safest and best to use. 

In nearly all the cases cited the antiseptics proved to be of some 
value in preventing the growths of the sap-stain fungus. Molds, 
however, are extremely resistant to chemical treatment and con¬ 
sequently are difficult to control. To quote from Lafar (28) ; 
“ Whether the waterproof character of some cell membranes, e. g., 
the conidia of Penicillium and Aspergillus, should be attributed to 


Fig. 17.—Barrels and steam-coil connections as used in the experimental dipping of 
red-oak spokes at one of the large spoke mills in the South. 

the deposition of excreted fatty or waxy substances must be left 
undetermined. Biologically this phenomenon is important, since it 
prevents the penetration of toxic substances from the aqueous 
medium and thereby also opposes the attempts of the mycologist to 
kill such fungi by means of aqueous toxic solutions.” Since, as has 
been stated repeatedly, molds develop largely on the surface of the 
timber and are sufficiently removed during the several finishing proc¬ 
esses to which the timber is sooner or later subjected, their presence 
in most cases should occasion but little concern in connection with 
vehicle stock. 

EXPERIMENTAL DIPPING OF RED-OAK SPOKES. 

DIPPING. 

In July, 1918, several series of experiments were performed by 
the writer in cooperation with one of the large spoke mills of the 






SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 39 

South. It was desired to test in a more practical way some of the 
antiseptics that had been used on a small scale during prelimi¬ 
nary experiments at the Madison laboratory. In these experi¬ 
ments first-grade escort spokes 2J by 2J by 27 inches long of red oak 
were used. They were selected mainly for two reasons: First, red 
oak in a green condition was the wood, of all those used at this par¬ 
ticular mill, which seemed to be the most liable to mold and sap- 
stain; second, the escort spoke was convenient to handle in connec¬ 
tion with the dipping apparatus employed. 

All spokes were taken directly from the warehouse after turning 
and grading. It was noted that 80 to 90 per cent of them contained 
sapwood varying in amount from 5 to 100 per cent. 

In lieu of dipping tanks it was decided to use whisky barrels of 
50-gallon capacity. Three of these were placed on a platform in 
the mill yard beside the tracks upon which the trucks were operated. 
One barrel was equipped with a steam coil of bent J-inch iron pipe 
provided with shut-off valves (fig. 17). This coil, when connected 
with the main steam boiler, supplied the necessary heat for main¬ 
taining the temperature of the dipping solutions. A piece of cor¬ 
rugated, galvanized-iron plate, approximately 2 by 6 feet, when 
supported in a slanting position with the lower end resting upon the 
top of the barrel, served as a drain board. Iron tongs similar to 
those used by blacksmiths, hydrometers, thermometers, and a gallon 
measure completed the list of essential apparatus. 

The following antiseptics were applied in the form of solutions or 
in a dry state: 

(а) Barrett’s grade 1 liquid creosote, 10 per cent by volume. 

Perfection kerosene oil, 90 per cent by volume. 

Temperature, 80° to 90° F. 

(б) Barrett’s grade 1 liquid creosote, 10 per cent by volume. 

Perfection kerosene oil, 90 per cent by volume. 

Temperature, 150° to 155° F. 

(c) Powdered borax, 5 per cent by weight. 

Water, 95 per cent by weight. 

Temperature, 80° to 90° F. 

( d) Mercuric chlorid (C. P.), 1 per cent by weight. 

Hydrochloric acid (commercial), 1 per cent by weight. 

Water, 9S per cent by weight. 

Temperature, 80° to 90° F. 

(c) Dry salt (finely grained). 

( f ) Dry quicklime (finely powdered). 

The spokes were conveyed to the dipping barrels on trucks. There 
they were grasped by means of the iron tongs, immersed from 5 to 
10 seconds in the bath, and then placed on the corrugated-iron drain 
board (fig. 18). When practically all of the excess liquid had 
drained off they were again grasped with the tongs, loaded upon 
another truck, and wheeled to the north end of one of the open sheds 


40 BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. 

in the yard. There they were unloaded, close piled, and allowed to 
remain until ready for shipment. 

During the dipping operation it was observed that in some cases 
as many as 10 to 15 per cent of the untreated spokes in a given truck 
load showed the presence of sap-stain. In one lot the number show¬ 
ing sap-stain and mold was estimated at 50 per cent. Other lots 
were practically free from fungi. During the experimental work 
the weather was for the most part hot and dry. Following one or 
two light showers the amount of mold on untreated material showed 
a marked gain. 

The methods of dipping were similar for all baths except in the 
case of the hot creosote. Here, the steam coil was employed and a 



Fig. 18.—The experimental dipping of red-oak spokes green from the lathe. 


temperature of 150° to 155° F. maintained. One barrel served for 
both cold and hot creosote. The borax was dissolved by aid of the 
steam coil in the second barrel. A third barrel was necessary for 
the mercuric-chlorid dip. Thermometer and hydrometer readings 
were taken at frequent intervals, and whenever necessary correc¬ 
tions were made to maintain a constant temperature and concentra¬ 
tion in the bath. 

Incidentally, it was noticed that ambrosia beetles were very 
quickly killed by the creosote dip, a point of importance to consider 
in controlling insect pests which at times, especially during warm 
and damp weather, are said to cause considerable losses in piled 
lumber. 23 (Weiss, 56, p. 18-20.) 

23 A certain species of beetle, Dendroctonus ponderosae Hopk., has been mentioned by 
Von Schrenk (.$1) as being partly responsible for the dissemination of the spores of the 
blue-stain fungus. 









SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 


41 


Both cold and hot solutions of creosote may cause considerable 
irritation, and in some cases blistering, when brought in contact with 
the skin. By proper use of the tongs, however, this trouble was 
avoided. Rubber gloves were worn during the dipping of spokes 
in the solutions of mercuric chlorid, since that salt, as already 
stated, is a deadly poison when taken internally and is sometimes 
absorbed through the skin when solutions are handled continuously. 

Many metals, such as iron and zinc, possess the common property 
of precipitating metallic mercury from the solutions of its salts. 
For this reason the iron tongs and other metallic objects could not 
be used in connection with the mercuric-chlorid dip. 

The spokes that were treated with salt or lime were placed, a few 
at a time, in wooden boxes containing the respective substances in a 
finely powdered state and were rolled to distribute the chemicals 
over them as evenly as possible. The excess was shaken off. They 
were then close piled in one section of the warehouse. After 24 
hours the lime coating showed a marked tendency to absorb moisture 
and cake. Moreover, it turned the wood dark. For this reason the 
liming was discontinued after 300 spokes had been treated. The 
salted spokes soon became exceedingly moist, due to the hygroscopic 
nature of the salt. The antiseptics used and the number of spokes 
treated in the different lots follow: 

(a) 10 per cent creosote in kerosene, cold_5.100 

( b) 10 per cent creosote in kerosene, hot_5,100 

(c) 5 per cent borax in water_1,013 

(d\ 1 per cent mercuric chlorid plus 1 per cent hydro¬ 
chloric acid_1, 000 

(e) Dry salt_1,032 

(f) Dry quicklime- 300 

The first lot went forward in a box car loaded to capacity with 
5,000 cold-creosoted spokes, 5,000 that had been hot creosoted, 800 
spokes that had been dipped in mercuric chlorid, and 350 that were 
untreated. It was originally intended to ship the other lots at the 
same time. The car, however, was found to be too small, so the 
borax-treated, salted, and limed spokes went forward at a later date. 

Many of the cold-creosoted spokes that had lain in the shed for 
• two to three weeks awaiting shipment were slightly molded. It was 
noticed that those with the mold were taken from that part of the 
pile that had suffered most from poor ventilation, namely, near the 
bottom and in the rear. The spokes in the other lots at that time 
seemed to be free from mold or sap-stain. 

METHOD OF LOADING CAR NO. 1. 

The spokes were stacked in transverse ricks, beginning at the end 
of the car and working toward the doorway. Each rick was built 
up in the following manner. A row consisting of five pairs of spokes 








42 BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. 

all parallel to the length of the car was laid across the floor. An 
interval of perhaps 1 or 2 inches separated the members of a pair, 
and the distance between successive pairs was made a little less 
than the length of a spoke. Upon either end of these was laid a 
single transverse row of spokes. A third layer similar to the first 
and a fourth similar to the second were then laid down. With two 
more alternate layers a comparatively open base six layers in height 
and providing for partial aeration of the ricks was constructed. 
Upon this base the remaining spokes of the rick were close piled in 
successive layers, two or three spokes in depth. Each alternate 
horizontal layer was placed at a slight angle to those directly above 
and below, but all had a general direction lengthwise of the car. 
Each rick when built to within 2 feet or so of the roof contained 
on an average 833 spokes. As soon as one end of the car had been 
filled ricks were placed in the opposite end. In the doorway three 
longitudinal ricks were constructed and any space remaining was 
filled in with loose spokes. In this particular case one end of the 
car was stacked with the hot-creosoted spokes, the opposite end and 
1^ ricks in the doorway being stacked with the cold-creosoted spokes. 
Parts of two ricks in or near the doorway comprised spokes treated 
with mercuric chlorid, and the remainder consisted of untreated spokes 
thrown in loosely between the longitudinal ricks antf the doorway. 
Both doorways were boarded up with 6-inch boards spaced 1J inches 
apart, and both doors were left open for about 1 foot. This car left 
the yard on July 24, consigned to one of the large vehicle factories 
of the North and reached its destination on August 14. On August 
15 and 16 it was unloaded and inspected by C. J. Humphrey and the 
writer. During the time that the car was in transit the weather was 
in general hot and dry, although local showers may have been 
encountered. 

CONDITION OF SPOKES IN CAR NO. 1 UPON ARRIVAL AT DESTINATION. 

The inspection at the time of arrival was very thorough, each spoke 
being handled separately and a record kept of the number showing 
mold in any degree. Observations were also made, in a general way, 
of the extent of sap-stain and incipient rot. No attempt was made to 
discriminate between heavy and light infections, as these largely 
depended, with a given preservative, on the position of the spokes 
in the ricks or in the car with respect to the amount of ventilation 
received. In general, the top layers to a depth of 15 to 18 inches 
showed very little mold; likewise, the loosely arranged bases were 
quite free or comparatively so. The molds consisted for the most 
part of fluffy white to tawny mycelium, together with a compara¬ 
tively small amount of green Penicillium. In the case of the cold- 
creosoted spokes, there seemed to be an increase over the amount 


SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 


43 


which was observed on the same spokes at the time of loading. For 
convenience in presentation, the data relative to location in the car 
and condition are given in Table I. 

Table I. — Condition of the red-oak spokes in car No. 1 upon arrival at its 

destination. 


Location in car.« 

Antiseptic. 

Condition. 

Percent¬ 

age 

molded 
(based on 
833 

spokes 
per rick). 

Forward end of the car: 
Loose in the door- 

Untreated. 

Free from mold or sap-stain; a few badly 
checked. 

None with mold or sap-stain; not so many 


way. 

Stacked in the door- 

Mercuric chlorid and 


way and first 

hydrochloric acid. 

checked as in the untreated lot. 


rick. 

First rick. 

Hot creosote at 150° to 

None with mold; no sap-stain. 

t 

Second rick. 

155° F. 

68 with mold; no sap-stain. 

8.2 

Third rick. 

.do. 

431 with mold; no sap-stain. 

51. 7 

Fourth rick. 

.do. 

277 with mold; no sap-stain. 

33. 2 

Fifth rick. 

.do_ 

218 with mold; no sap-stain. . 

26. 2 

Sixth rick (end of 
the car). 

Opposite end of the car: 
Stacked in the door- 

.do. 

222 with mold; no sap-stain. 

26. 7 

Cold creosote at 80° to 

69 with mold; no sap-stain... 

8.3 

way and first rick. 
Second rick . 

90° F. 

.do. 

492 with mold; no sap-stain. 

59. 1 

Third rick 

. .do. 

348 with mold; no sap-stain. 

41. 8 

Fourth rick 

.do. 

207 with mold; no sap-stain.. 

24. 8 

Fifth rick (end of 
the car). 

...do. 

142 with mold; no sap-stain.. 

17.0 




a Ricks are in each case numbered from the first transverse rick on either side of the area between the 
doors and extending back to the ends of the car. 


It will be seen from Table I that the spokes that were placed in the 
doorway where better ventilation could be had did not mold or 
sap-stain. Those that were the most exposed, however, were inclined 
to suffer from checking. The largest proportion of molding took 
place in the second or third ricks, but in no case was this accompanied 
by sap-stain, and in no instance was it severe enough to necessitate 
culling. The considerable reduction in the fourth and fifth ricks, 
which was most marked in the rear end of the car, is difficult to ex¬ 
plain. In the forward end, the motion of the train caused the last 
rick to slide away from the end of the car, and thus somewhat im¬ 
proved the ventilation. It is possible, then, that in the rear end the 
tendency of the mass of spokes to surge backward and forward when¬ 
ever the continuous passage of the car was interrupted, together with 
the fact that a hole existed in the bottom of the car due to the breaking 
of a floor plank, may have provided sufficient ventilation to account 
for the low percentage of mold in the fourth and fifth ricks. 

It was noted that the stage in the development of the mold on the 
creosoted material was an early one. namely, a white, fluffy mycelium, 
which in most cases had not advanced to the spore-producing condi¬ 
tion. This indicates a retarding effect due to the treatment. It is 



















































44 


BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. 


also evident that the creosote, though unable entirely to control the 
mold, seemed to prevent the development of sap-stain. From the 
evidence it would also appear that heating the creosote to 150° or 155° 
F. does not increase its effectiveness to any marked degree, the differ¬ 
ence in the percentage of moldy spokes in the two treatments being 
less than 1 per cent. 

METHOD OF LOADING CAR NO. 2. 



The second car, containing 1,032 salted, 1,013 borax-treated, 300 
lime-treated red-oak, and the remainder untreated, white-oak escort 

spokes, was loaded 
on August 3 and 5. 

Those spokes that 
had been salted were 
exceedingly moist, 
owing to the hygro¬ 
scopic property of 
the salt. On manv 

i/ 

of these species of 
Penicillium were 
found. The limed 
spokes were dark in 
color and in a few 
cases seemed to be 
developing sap-stain. 
The borax-treated 
spakes were appar¬ 
ently quite free from 
fungi. 

The method used 
for stacking the 
spokes in the second 
car differed somewhat 
from that in the first. The base of each rick was constructed in 
the same manner, though of four instead of six layers. Upon this 
base the spokes were carefully stacked, using two 1 J-inch by Finch 
crossers of elm between successive layers (fig. 19). Each rick held 
on an average 840 spokes. The doorways were closed in the same 
manner as in car No. 1. This consignment left the yard on August 
6 and arrived at the same factory located in the North on August 20, 
a period of two weeks in transit. During this time the weather was 
hot and comparatively dry. 


Fig. 19. —“ Ricking,” or stacking, treated escort spokes in 

a box car (car No. 2). 


CONDITION OF SPOKES IN CAR NO. 2 UPON ARRIVAL AT DESTINATION. 

On August 21 the spokes were unloaded and inspected by C. J. 
Humphrey and the writer. Table II gives the location of the dif¬ 
ferent lots and their condition upon arrival. 

















SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 45 

Table II .—Condition of the spokes in car No. 2 upon arrival at its destination. 


Location in car. 


Material. 


Antiseptic. 


Condition. 


Ricks in the end of 
the car contain¬ 
ing treated spokes: 
First rick'. 

Seoond rick.... 


White oak.. 

_do. 

• Red oak 


Untreated;. 

A few untreated layers at top 
Remaining layers borax, 5 


147 moldy: a few sap-stained 

1 moldy... 

67 moldy; many sap-stained. 


Percent¬ 

age 

molded 
(based 
on 840 
spokes 
per rick). 


17.5 
. 1 
7.9 


Third rick. 
Fourth rick 


_do 

_do 

[....do 
.do 


per cent. 

Top layers borax, 5 per cent. 
Middle layers lime. 

Bottom layer salt. 

Salt. 


Fifth rick. 

Sixthrick. 

Ricks in the door¬ 
way and in the 
opposite end of 
the car: 

In doorway 

First rick. 

Second rick 
Third to sixth 
ricks. 


White oak. 
... .do. 


do 

do 

do 

do 


Untreated 
_do.... 


do 

do 

do 

do 


7 moldy; many sap-stained.. 
4 moldy; some sap-stained... 
Spokes very dark in color. 

34 moldy; some sap-stained.. 
300 moldy; many with Pen- 
icilliumin all parts of rick, 
badly damaged. 

330 moldy; much sap-stain.. 
292 moldy; much sap-stain.. 


. 8 

.4 

4.0 
35. 7 


39.3 
34. 8 


No mold; no sap-stain. 

87 moldy: many sap-stained 
312 moldy: many sap-stained 
Not examined. 


0 

10. 4 
37.1 


The proportion of infected spokes, based on the total number in 
the different lots in the end of the car containing these spokes, is: 

Untreated_29 per cent moldy. 

Salted_32. 3 per cent moldy. 

Borax (treated)_ 7. 3 per cent moldy. 

Lime (treated)_ 1. 3 per cent moldy. 

These figures can by no means be used as a basis for an exact com¬ 
parison of the values of the three preservatives. The location of the 
ricks in the car introduces another and very, important factor. To 
note whether the hygroscopic property of the salt had a tendency to 
affect the humidity in the end of the car in which the salted spokes 
were stacked, thus influencing, perhaps, the amount of molding in 
adjacent lots, it was decided to observe the unloading of the spokes 
in the opposite end of the car. After two ricks had been unloaded, 
however, it became evident that this was not the case, as conditions 
in that end were practically the same as in the first. From the data 
derived, at least from this lot, given in Table II, it would seem that 
salt when applied dry to green spokes is of little value in conti oiling 
either sap-stain or mold. Lime, though effective in preventing both 
mold and sap-stain, yet because of its darkening effect on the wood 
and its tendency to form calcium carbonate, which cases over the 
surface and is said to dull the knives used in subsequent piocesses of 
manufacture, is debarred from further consideration. Lorax, how¬ 
ever, with 7.3 per cent moldy spokes, seems to be somewhat effective 
against mold, but of less value in controlling sap-stain. 






















































46 


BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. 


SUMMARY OF OBSERVATIONS. 


Creosote dipping seemed to prevent sap-staining, but it had little 
effect upon mold. In no way did it detract from the sale value of 
the spokes. 

The creosote bath at 80° to 90° F. was nearly as effective as at 150° 
to 155° F. 



Mercuric chlorid, 1 per cent, seemed to be very effective in con¬ 
trolling both sap- 
stain and mold. 

Borax solution, 5 
per cent, appeared 
to be somew y hat ef¬ 
fective in control¬ 
ling mold, but of less 
value in regard to 
sap-stain. 

The use of lime in 
the treatment of 
spokes was not satis¬ 
factory, on account 
of its darkening ef¬ 
fect on the wood, the 
covering up of phys¬ 
ical defects, and the 
probability of dull¬ 
ing the knives used 
in later processes of 
manufacture. 

Salt sprinkled over 
the spokes was of no 
value in preventing 
either mold or sap- 
stain. 

The ventilation of 
spokes in a box car is 
an important factor. 

Those spokes in the doorway, even if untreated, usually have but little 
tendency to mold or sap-stain. 

Practically none of the spokes in either car were culled on account 
of defects due to fungi, although a few in the areaway between the 
doors were thrown out on account of slight checking. 

No incipient decay was found in any of the material. . 


Fig. 20.—Green turned spokes cross piled in open or venti¬ 
lated sheds. Green spokes are sometimes allowed to 
surface dry in this manner for one to two months pre¬ 
paratory to shipping in box cars. 












SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 


47 


EXPERIMENTAL DIPPING OF RED-OAK BLOCKS AT THE LABORATORY OF FOREST 

PATHOLOGY, MADISON, WIS. 



A comparison of the specific antiseptic values of the chemical sub¬ 
stances employed in the spoke-dipping experiments can hardly be 
made, since these substances were not used in solutions of uniform 
strength. To determine, if possible, the comparative values of these 
and several other common antiseptics and preservatives in the control 
of mold and sap-stain 
fungi, several series 
of experiments were 
undertaken at the 
Madi son laboratory. 

AVhere possible, solu¬ 
tions were made up 
to a calculated value 
of 1 per cent actual 
weight of anhydrous 
salt. The hygroscopic 
substances—sodium 
chlorid, calcium 
chlorid, and glyc¬ 
erin—were added in 
certain instances to 
determine whether or not they would increase the efficiency of the 
preservative by keeping the surface of the treated wood moist. A 
list of the substances used follows: 


Fig. 21.—Storage of spokes in a warehouse. The truck 
spokes at the left have just been painted by girls with 
a resin-linseed oil mixture to prevent checking. 




Alum (potassium). 

Ammonium fluorid. 

Bleaching powder. 

Borax. 

Copper sulphate. 

Lead acetate. 

Lead nitrate. 

Magnesium silicofluorid. 
Mercuric - chlorid. 

Mercuric chlorid and hydro¬ 
chloric acid, 1 per cent. 


Potassium chlorate. 
Sodium fluorid. 
Sodium bifluorid. 
Zinc silicofluorid. 
Creosote in kerosene. 
Formalin. 

Lysol. 

Mykantin. 

Orthonitrophenol. 

Rongalite. 


Red-oak blocks f by J by inches long, sawed from the sapwood 
of summer-cut logs, were used in each case. Ten blocks constituted 
a group. The individual blocks of a group were immersed for ap¬ 
proximately 10 seconds in one of the respective solutions, drained, 
and then sprayed on all six sides with a water suspension of the 
spores taken from the same cultures as those used in the steaming 
experiments. 24 The sprayed blocks of each group were then close 
piled and placed in the tile chamber mentioned on page 29. An in- 


24 See page 29 for the list of fungi. 








48 


BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. 


terval of at least 14 inches was maintained between adjacent groups. 
In the tile chamber the blocks were subjected to a temperature aver¬ 
aging 80° F. and a relative humidity varying from 85 to 100 per cent. 
At the end of three to four weeks all blocks were carefully examined. 
The following observations were made at that time: 

None of the preservatives was entirely effective in controlling 
mold when used in concentrations of 1 per cent. 

Blocks dipped in sodium carbonate, sodium bicarbonate, sodium 
fluorid, sodium bifluorid, ammonium fluorid, magnesium silicofluorid, 
zinc silicofluorid, and bleaching powder became badly molded. 

Potassium (alum), potassium chlorate, and copper sulphate seemed 
to stimulate all or certain species of the fungi used. The last seemed 
to incite the growth of Aspergillus niger in particular. 




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&£ PC/PPO. 



ppopg ppt ro t opo s/p /ps 


Fig. 22.—Diagram illustrating the method of loading used by one of the large wheel fac¬ 
tories and recommended by the wood-stock committee in connection with vehicle stock. 


Borax was effective in controlling the sap-stain fungus ( Cerato - 
stom.el.la sp.). Though it did not entirely prevent the growth of mold, 
the amount of mold that did develop was very slight in comparison 
with that on the blocks treated with the other preservative solutions. 
I nder these circumstances it compared favorably with 1 per cent 
mercuric chlorid. 

The addition of the hygroscopic substances—sodium chlorid, cal¬ 
cium chlorid, and glycerin—to the solutions of the preservatives 
apparently did not increase their efficiency. 

Of the organic compounds and mixtures tested here, creosote in 
kerosene gave the best results, while mykantin stood second. The 
latter, however, stained the wood yellow, a property which would 
prohibit its use for many purposes. 
















































































































































































SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 49 

STORAGE OF GREEN DIMENSION, SAWED, OR TURNED STOCK AT THE MILL. 


If it becomes necessary to store dimension or turned green stock 
without giving it the protection referred to, cross piling or stripping 
in properly ventilated sheds is absolutely essential (figs. 20 and 
21). All strips should be narrow and at least three-fourths of 
an inch, but preferably 1 inch, in thickness and should be thoroughly 
seasoned or given some antiseptic treatment. 


HANDLING GREEN DIMENSION, SAWED, OR TURNED STOCK IN TRANSIT. 



If it becomes necessary to ship green dimension, sawed, or turned 
stock and planks during the late spring and summer months, atten¬ 
tion must be paid to the cleanliness and ventilation of such material 
while in transit. 25 
Cattle, vegetable, or 
ventilated box cars 
which have been 
previously cleaned 
are to be preferred 
for small stock. In 
ventilated box cars 
the end doors should 
be cleated open. If 
only box cars of the 
ordinary type are 
available, the ma¬ 
terial should be 
piled according to 
methods similar to 
the one shown in 
figure 22. In the 
case of spokes and 
sawed billets, a cross- 
piled foundation, 
four to six courses 
high, is recommended 
in addition to the 


in a box car. Elm strips 
between the courses. 


directions fri veil Fig. 23.—Artillery spokes “ ricked ” 

, r, one-half inch by 11 inches used 

(figs. 23 and 24). 

When doors of box cars are loosely boarded up (fig. 25) or cleated 
open (figs. 9 and 22), it is recommended that they be spiked, that the 
bill of lading bear an indorsement to the effect that the doors were 
left open and cleated at the request of the shipper, and finally that 


25 The directions given under “ Provisions for the proper ventilation of stock in transit,” 
page 23, apply here. 

























50 BULLETIN 1037, U. S. DEPARTMENT OF AGRICULTURE. 


a notice similar to that devised by one of the wheel companies 

and cited in Bulletin No. 30 of the wood-stock committee 26 be nailed 
to the car, reading as follows: 


TAKE NOTICE.—Do not Close Doobs. —The lumber in this car is 
green and is carefully cross piled that there may be good circulation of 
air through the stock. The doors are left partly open and cleated by the 
shipper upon request of the consignee. If the doors are closed the stock 
will be liable to damage in transit. 

Should this car break down in transit, making it necessary to transfer 
the stock to another car, it should be stacked in the car in the same 
manner and doors left open in the same way. 



The use of box cars is usually demanded by those in charge of 
bending mills where green rim stock is to be shipped. These cars 

expose the stock to 
less damage from 
checking. Unless at¬ 
tention is paid to 
stripping or some 
method of piling so as 
to insure ventilation, 
however, molding and 
sap-staining may re¬ 
sult. One method 
used for the piling of 
rim strips in cars is 
shown in figure 26. 


Fig. 24.—Artillery spokes “ ricked ” in a box car. A SUMMARY 

cross-piled base, strips, and open-boarded doorway are 

important details in the provision for proper ventilation jg evident that 

of the stock while in transit. .. .. » 

the prevention ox sap- 

stain, mold, and incipient decay in green material, and in vehicle stock 
in particular, lies in a combination of remedial factors, the following 
being especially important: Care in the selection of raw stock in 
order to obtain, if possible, material free from fungous infections; 
expedition in the movement of raw stock from the felling of the logs 
to that time in the process of manufacture when the material becomes 
sufficiently dry to resist the attacks of fungi; provision at all times 
for ample ventilation of the stock that it may quickly become at least 
surface dried, thus making it difficult for the fungous spores to obtain 
from the exposed sapwood the moisture necessary for germination; 


20 National Implement and Vehicle Association and other Vehicle and Vehicle Parts 
Manufacturers. Information Division of the Wagon and Vehicle Committee and the 
Wheel Manufacturers’ War Service Committee. Wood Stock Committee. Sap-stain and 
mold in transit. Nat. Implement and Vehicle Assoc., etc., Bui. 30, 5 p. 1918. A. B. 
Tliielens, chairman. Typewritten. 









SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 


51 



the kiln drying of the stock wherever possible and whenever the cost 
will permit; and in special cases steam treatment or the use of anti¬ 
septic dips, followed by proper piling to insure ample ventilation. 

It must be continu¬ 
ally borne in mind 
that none of these is 
by itself a sovereign 
remedy. Preservative 
dips or steam treat¬ 
ment were not in 
themselves, under the 
emergency manufac¬ 
turing conditions in¬ 
cident to the war, by 
any means sufficient 
to control molding of 
green stock when close 
piled in storage ware • 
houses or while in 
transit in box cars. 

In connection with this investigation, it should also be borne in 
mind that we are dealing with three distinct groups of fungi, namely, 
the molds, staining organisms, and true wood-destroying organisms, 
the antiseptics being more efficient against the last two groups than 

the first. As far as 
is known, neither 
molds nor staining 
fungi cause any ap¬ 
preciable diminution 
in the strength of 
timber and hence are 
Fig. 26.—Zigzag method of piling rim strips in box cars. unimportant in Ve¬ 
hicle manufacture from the standpoint of strength and probably 
durability. The staining fungi can be controlled to a certain extent 
by the intelligent use of antiseptics and possibly by steaming, and 
it seems reasonable, in the light of experience, to suppose that the 
development of wood-destroying fungi can also be prevented. 


Fig. 25.—A box car loaded with spokes and ready for ship¬ 
ment. Spaces of 1| inches are left between adjacent 
boards nailed across the doorways to allow for venti¬ 
lation of the stock while in transit. 


























































LITERATURE CITED. 


(1) Aso, Keijiro. 

1901. On the role of oxydase in the preparation of commercial tea. In 
Bill. Col. Agr., Tokyo Imp. Univ., v. 4, no. 4, p. 255-259. 

(2) 1902. On oxidizing enzyms in the vegetable body. In Bui. Col. Agr., 

Tokyo Imp. Univ., v. 5, no. 2, p. 207-235. 

(3) 1903. On the chemical nature of the oxidases. In Bui. Col. Agr., Tokyo 

Imp. Univ., v. 5, no. 4, p. 481-489. 

(4) 1905. Further observations on oxidases. In Bui. Col. Agr., Tokyo 

Imp. Univ., v. 6, no. 4, p. 371-374. 

(5) Bailey, Irving W. 

1910. Oxidizing enzymes and their relation to “ sap stain ” in lumber. 
In Bot. Gaz., v. 50, no. 2, p. 142-147. 

(6) Berkeley, M. J. 

1876. Notices of North American fungi. Nos. 927-932. Sphaeria jun- 
cina - Sphaeria semiimersa. In Grevillea, v. 4, no. 32, p. 146. 

(7) Betts, Harold S. 

1917. The seasoning of wood. U. S. Dept. Agr. Bui. 552, 28 p., 8 pi., 
18 fig. 

(8) Clark, Ernest Dunbar. 

1910. The plant oxidases. 113 p. Easton, Pa. Bibliography, p. 94-111. 
Diss.—Columbia Univ. 

(9) 1911. The nature and function of the plant oxidases. In Torreya, v. 

11, no. 2, p. 23-31; no. 3, p. 55-61; no. 4, p. 84-92, 101-110. 
Supplementary bibliography of papers recently published, p. 
109-110. 

(10) Ellis, J. B., and Everhart, B. M. 

1892. The North American Pyrenomycetes. A contribution to my cologic 
botany, 11, 3, 793 p., 41 pi. Newfield, N. J. 

(11) Frank, A. B. 

1895. Die Krankheiten der Pflanzen . . . Aufl. 2, Bd. 1. Breslau. 

(12) Freeman, E. M. 

1905. Minnesota Plant Diseases, xxiii, 432 p., illus. St. Paul. (Minn. 
Geol. and Nat. Hist. Survey, Rpt. Bot. Ser. V.) 

(13) Fries, Elias. 

1823. Systema mycologicum. . . v. 2. Lundae. 

(14) Fuckel, Leopold. 

1869-70. Symbolae Mycologicae. Beitriige zur Kenntniss der Rhein- 
ischen Pilze. 459 p., 6 pi. Wiesbaden. (Jahrb. Nassau. Ver. 
Naturk., Jahrg. 23/24.) 

(15) Gum Lumber Manufacturers’ Association. Technical Research Com¬ 

mittee. 

1914. Digest [of report]. In Lumber World Rev., v. 26, no. 10, p. 44. 

(16) Haas, Paul, and Hill, T. G. 

1913. An introduction to the chemistry of plant products. 401 p. Lon¬ 
don. 


SAP-STAIN, MOLD, AND DECAY IN GREEN WOOD. 


53 


(IT) Hartig, Robert. 

1878. Die ZersetzungserscheinUngen des Holzes der Nadelholzbaume und 
der Eicbe in forstlicher botaniscber und cbemiscber Rich- 
tung . . . Berlin. G, 151 p., 21 pi. (15 eol.). 

(18) 1900. Lehrbuch der Pflarzenkrankbeiten. Fur Botaniker, Forstleute, 

Landwirtbe und Gartner . . . Aufl. 3. 9, 324 p., 280 fig., 1 col. 
pi. Berlin. 

(19) Hedgcock, George Grant. 

1906. Studies upon some cliromogenic fungi wbicb discolor wood. In 

Mo. Bot. Gard. 17tb Ann. Rpt., p. 59-114, 3 fig., pi. 3-12. 

(20) 1911. Prevention of mold. In Barrel and box, v. 16, no. 4, p. 35. 

(21) Hubert, E. E. 

1921. Notes on sap-stain fungi. In Phytopathology, v. 11, no. 5. 

(22) Humphrey, C. J. 

1917. Timber storage conditions in the Eastern and Southern States 
with reference to decay problems. U. S. Dept. Agr. Bui. 510, 
43 p., 10 pi., 41 fig. 

(23) [1920.] The decay of ties in storage. 35 p., 8 p.. in text (pi. 1-3 

col.) Baltimore. 

(24) -and Fleming, Ruth M. 

1915. The toxicity to fungi of various oils and salts, particularly 

those used in wood preservation. 38 p., 4 pi. Bibliography, 
p. 37-38. 

(25) Hunt, George M. 

1916. The preservative treatment of farm timbers. U. S. Dept. Agr., 

Farmers’ Bui. 744, '32'p.', 17 fig. 

(26) Janka, Gabriel. 

1907. Die Einwirkung von Suss- und Salzwassern auf die gewerblichen 

Eigenschaften der‘ Hauptholzarten. Teil I. Untersuehungen 
und ergebnisse in meehanisch-technischer Hinsicht. In Mitt. 
Forstl. Yersuchsw. Osterr., Heft 33, p. 1-96, 16 fig. 

(27) Kastle, J. H. 

1910. The oxidases and other oxygen-catalysts concerned in biological 
conditions. U. S. Hyg. Lab. Bui. 59, 164 p. References to 
the literature, p. 141-161. 

(28) Lafar, Franz. 

1903. Technical Mycology: the Utilization of Micro-Organisms in the 
Arts and Manufactures. A Practical Handbook on Fermenta¬ 
tion ... v. 2, pt. 1. London. 

(29) Lindau, Gustav. 

1897. Sphaeriales. In Engler, Adolf, and Prantl, Karl. Die Natiir- 
lichen Pflanzenfamilien . . . Teil 1, AbL 1, p. 384-491, fig. 
252-288. Leipzig. 

(30) McBeth, I. G., and Scales, F. M. 

1913. The destruction of cellulose by bacteria and filamentous fungi. 
U. S. Dept. Agr., Bur. Plant Indus., Bui. 266, 52 p., 4 pi. 
Bibliography, p. 47-50. 

(31) Munch, Ernst. 

1907-08. Die Blaufiiule des Nadelholzes. In Naturw. Ztschr. Land. 

u. Forstw., Jahrg. 5, Heft 11, p. 531-573, 1907. Jahrg. 6, 
Heft 1, p. 32-47; Heft 6, p. 297-323, 1908. 33 fig. 





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